That is a HUGE question with many answers but a few places to start would be:
A "sticky" from Gearslutz which will help you to get started:
http://www.gearslutz.com/board/post-production-forum/229741-standard-mixing-levels-movie-theater-dvd-broadcast-tv-commercials-etc.html
For US broadcast standards you should read the ATSC's A85 document:
http://www.atsc.org/cms/index.php/standards/recommended-practices/185-a85-techniques-for-establishing-and-maintaining-audio-loudness-for-digital-television
For Europe there is a similar document put out by the EBU.
Here is an image of the NTSC, PAL, and SECAM breakdown in the world:
http://en.wikipedia.org/w/index.php?title=File:PAL-NTSC-SECAM.svg&page=1
Sample-rate and bit depth in relation to distribution is an equally huge question in and of itself and will require research of your own.
A few standards but there are MANY choices and reasons for choosing:
- 24bit/48kHz
- 192kpbs/48kHz
- 128kpbs/48kHz
- 192kpbs/44.1kHz
- 128kpbs/44.1kHz
I just want to reiterate that this is a huge question and the links I sent are starting points, if there are specific areas or delivery formats you are creating we might be able to be more specific.
There are so many delivery options from HD video to mobile audio and everything in between...Dolby AC3 encoded for Blu-Ray, Dolby E or Dolby Digital encoded HDCam tapes being sent to film festivals, DCP in theatres, Hulu streaming on your iPhone, HD Quicktime catapults to broadcast with WAV or even MP3 audio (not recommended but I have seen it). Delivery is something like the wild west.
Good luck and let us know if there are more specific questions.