A few wheel questions

Just a few questions my old man has that I cant answer.

Car in question is a 2002 Bonneville SSEI

Can 16" GM wheels be used in place of my 17" stock wheels?
Any issue with possibly larger rotors on 17" ?
What other issues besides the speedometer/odometer being incorrect?

Do replacement wheels need pressure sensors?
What happens of replacement wheels don’t have sensors?
Does my message system get confused and just post annoying message
that I can scroll past ?

You don’t actually have tpms sensors. It actually uses sensors to read the ride height.

bump