In mp3 192Kbps is a decent quality, When you use 128Kbps (which is the internet standard) you may get a little flange in the high frequencies...i.e above 15,000Hz. You can stick to 192Kbps if you don't mind the file size.
When considering the sampling rate, the physics goes like this.......... all you need is double the frequency you are using, you know that the human ear can only hear from 20hz to 20,000hz (20Khz) so if you double that you will get 40Khz, so anything above 40Khz should be fine. That is why people use 44.1Khz sampling rate as a standard. For better quality you can go 48, 96 or even 192Khz...but to a normal listener they don't make a difference at all. You can stick with 44.1Khz sample rate and make professional sound quality, so don't worry.