Freeware (Sourceforge, etc) audio processing programs

Audacity  (win, *nix, mac)
http://www.audacityteam.org/download/
record, edit, export  audio files.
(Bulk Convert/Transcode) First you load a file, then Import all the files you also want to to convert. Use Shift + Click or Ctrl + Click to select multiple files. Choose Export Multiple and then choose the desired audio format you want to convert to (it’s mp3 by default) and the destination you want the files to go

fre:ac – free audio converter
Audio converter and CD ripper for various formats
https://sourceforge.net/projects/bonkenc/?source=top3_dlp_t5

winLAME is an encoder for several audio formats, including mp3 (MPEG Layer 3), Ogg Vorbis and more. winLAME lets you set up the encoding process with an easy-to-use wizard-style user interface.
http://winlame.sourceforge.net/index.php  (Winlame 2010 b2)

Metadata ?
https://www.justmastering.com/article-embeddingmetadata.php

Metadata tagging
http://www.mp3tag.de/en/
The universal tag editor and more …
Mp3tag is a powerful and easy-to-use tool to edit metadata of audio files.
It supports batch tag-editing of ID3v1, ID3v2.3, ID3v2.4, iTunes MP4, WMA, Vorbis Comments and APE Tags for multiple files at once covering a variety of audio formats.

Audio CD Ripping
Exact Audio Copy http://exactaudiocopy.de/
Power users only, can be slow, but useful for the slightly damaged CD.

Fair Stairs  http://www.fairstars.com/cd_ripper/index.html
really good, fast, CDDB supported

Audio Grabber  http://www.audiograbber.org/
May install a BHO if you are not careful reading the dialog boxes

MEDIA PLAYER
VLC  Win, Android, *nix, Mac  https://www.videolan.org/vlc/
all others pale compared to it.

Audio Formats
WAV, OGG, FLAC and MP3 all have easily accessible, inexpensive or free, editing software
I do not recommend using software locked into one vendor or platform.

Music Song Database [CDDB ]
GRACENOTE is used by Nero SW when ID’ing CD’s while Ripping
http://www.freedb.org is useful by individual users, and some software

MP3 Bitrate suggestions

Mikes personal summary:

Archival Storage: FLAC (lossless & metadata)
Show content:   MP3 (much smaller files, & metadata)
Constant Bit Rate (some players have trouble with Variable)

MP3 @
48kbps  Talk only, NEVER music
96Kbps  Talk only, Music will suffer some
128kbps Most music, slight artifacts
160Kbps Really great audio source material
192Kbps Outstanding audio source material, file size getting larger….
256kbps Huge files, near CD quality,
must have dog’s ears to discern improvement over 192kbps

////////     and for the sources of my opinions:    \\\\\\\\\\\

http://www.cnet.com/news/which-mp3-bit-rate-should-i-use/
The absolute lowest   128kbps
The happy medium between small file sizes and true CD quality audio is a 256kbps bit rate. This offers vastly superior sound quality over 128kbps, without eating up too much disk space. The difference in quality between 128kbps and 256kbps is vast and immediately obvious — your favourite tunes encoded at 256kbps will sound stunning in comparison to the same tracks encoded at 128kbps.
One final consideration should be to encode MP3s using a ‘variable bit rate’ instead of a ‘constant bit rate’. Using VBR allows the MP3 encoder to use lower bit rates during quieter or less complex parts of a song, and significantly higher bit rates during more complex sections.

http://www.soundonsound.com/sound-advice/q-can-you-help-me-mp3-file-conversion
MP3 files can be created at CBR (Constant Bit Rate) values from 8Kbps to 320Kbps. Spoken word is still perfectly intelligible down to about 24Kbps, which is usually perfectly sufficient for podcasts, talk radio, and so on. Solo acoustic music performances could be acceptable at 48Kbps, although 64Kbps is probably more in line with AM radio quality.
For reasonable-quality ensemble music, many people consider 128Kbps a good baseline, especially if the intended destination is computer speakers or in-car audio systems. However, when listening on a hi-fi or on studio playback gear, many musicians find 128Kbps difficult to listen to, especially since the frequency response falls off rapidly above 16kHz, high‑frequency sounds such as cymbals sound distinctly harsh, and you can often hear a low-level background ‘warbling’ sound, which is the main reason that some people dislike this rate.
If you’re looking for the best compromise for your MP3 files between compression ratio and audio quality, bit-rates of 160Kbps or 192Kbps are generally recommended, with 192Kbps, in particular — often being classed as ‘near CD’ quality — suitable for complex music or tracks with lots of bass content. Only on expensive playback systems can most people tell the difference between 192Kbps and CD quality.

http://www.missionarygeek.com/2013/05/suggested-audacity-settings-for-mp3-export/
(Lots of good data, in english (not geek) here, read all the way through this site)
Bit Rate Mode
The different bit rate options can give you smaller file sizes, but at the cost of potential compatibility and quality issues. I always choose Constant (also called CBR in some editing software) on this option regardless of the project I am working on. This gives the largest file size for compatible settings of the various options, but also gives me more confidence in the compatibility of the final file.
For a podcast that is is just spoken word with no music, I usually choose 96 kbps. You can probably go a bit lower before you start to hear sound quality issues. Much higher than that and you won’t be able to tell a quality difference in the spoken audio.
If, however, I am doing audio that will go into a video file–which I do for my video podcast–and I know that the MP3 will get re-encoded later with the video, then I will choose a higher sound quality. Usually I do these at 192 kbps. The sound quality doesn’t have to be perfect and I am also working with spoken word only, no music. If I wanted to make sure my sound was the best quality it could be for my video project (or if I were using music) then I would choose 320 kbps or export a WAV file.
For anything with music, then the lowest you probably want to go is 128 kbps if the music is background or ancillary and is not the focus of the sound file. If you are trying to show the quality of the music then you should choose 256 or 320 kbps for the best quality MP3 you can get.

http://www.mediamonkey.com/wiki/index.php/MP3_Encoding_Settings
(this site has a easy to read table)

https://blog.codinghorror.com/the-great-mp3-bitrate-experiment/
Anyhow, previous research and my own experiments led me to write Getting the Best Bang for Your Byte seven years ago. I concluded that nobody could really hear the difference between a raw CD track and an MP3 using a decent encoder at a variable bit rate averaging around 160kbps………The difference between the 320kbps track and the 192kbps track is more rational to argue about. But it’s still 1.6 times the size. Yes, we have tons more bandwidth and storage and power today, but storage space on your mobile device will never be free, nor will bandwidth or storage in the cloud, where I think most of this stuff should ultimately reside. And all other things being equal, wouldn’t you rather be able to fit 200 songs on your device instead of 100? Wouldn’t you rather be able to download 10 tracks in the same time instead of 5? Efficiency, that’s where it’s at. Particularly when people with dog’s ears wouldn’t even be able to hear the difference.

http://wiki.hydrogenaud.io/index.php?title=Lame#Very_high_quality:_HiFi.2C_home.2C_or_quiet_listening.2C_with_best_file_size
<http://wiki.hydrogenaud.io/index.php?title=Lame#Very_high_quality:_HiFi.2C_home.2C_or_quiet_listening.2C_with_best_file_size>
excerpt   Maximum quality and archiving

Maximum quality is achieved when, regardless of listening conditions, you are unable to detect a difference between the MP3 and the original. As demonstrated by blind ABX tests, LAME-encoded MP3s typically achieve this level of transparency when encoded with the default settings, at bitrates well below maximum. Encoding with higher-bitrate settings will have no effect on the perceived quality.
For archiving, only lossless formats like WavPack, FLAC, etc. are ideal; they will preserve the audio with no changes, sample-for-sample, regardless of encoder settings. In contrast, lossy formats like MP3 are designed to save space by changing the audio in subtle, often imperceptible ways, even at the encoder’s maximum settings.
Very high quality: HiFi, home, or quiet listening, with best file size
-V0 (~245 kbps), -V1 (~225 kbps), -V2 (~190 kbps) or -V3 (~175 kbps) are recommended.
These VBR settings will normally produce transparent results. Audible differences between these presets may exist, but are rare.