On the sound side, I don't think there is an audio receiver that would allow the connections you're seeking. However, if you are considering a soundbar for use with the projector, most have their own amplification channels and do not require a receiver or amplifier. There are good units for as little as $100 all the way up to the multiple thousands of dollars. And, don't judge any soundbar by the price or any normal criteria you would use for selecting a hi-fi or surround system.
As far as the video switching, I know there are professional units out there that can accomplish what you are looking for, but again, you are probably talking at least one thousand dollars, probably more. Depending on what content you would be using with your projector, you would probably come out better purchasing dedicated components (Blu-Ray) to connect directly to the projector.