Item 3), Yes, why 44.1kHz when most other audio sampling rates are an integer multiple of 1000Hz? There is a good reason for this, it stems from the two different line rates of 15,625Hz (EU) and 15.750kHz (US) used for most analogue TV. Klaas Robers did explain exactly the maths behind this a few years ago. It seemed sensible, but I cannot recall now how was derived. As the CD has gone the way of Beta, VHS and others (dead) it really doesn't matter anymore. 22,050Hz and 11,025Hz are simply sub-multiples of it. Even the sampling rate of the telephone system at 64,000
bits/sec comes out to a nice round 8,000
bytes/sec (8kHz) - a theoretical audio bandwidth of 4kHz - good enough for telephony.
The other items really shouldn't need any further expansion, but I will if you're still quizzical or confused.
Steve A.
Here's a good explanation of audio, compression, sampling rates and bit-depth from the BBC...video too...(just think of NBTV video as audio - it's just a special type of audio)....
https://www.bbc.co.uk/bitesize/guides/z ... revision/1Factoid:- The sampling rate of DVD audio is 48kHz, not 44.1kHz. Recording studios often use 96kHz or 192kHz sampling at 24 bits for mastering, when the mix-down is complete it is bit-reduced and sample-rate reduced to 48 or 44.1kHz at 16 bits as required.