Does Sonic 3 Complete go here also?

Over here: https://www.speedrun.com/s3c

Sonic 3 Complete is considered for running the game glitchless.

Okay cause I can't glitch games. Will a separate emulator called Retro Gen work for playing on?

The rulesets specify which emulators can be used, please make sure to read those before asking questions.

Is sound required to submit a run?

Yeah they want that extra bit of verification. There was another thread where somebody asked this question and that was the response there as well.