General bike questions

Hey guys, i just bought me a 2004 cbr600rr a few days ago and i know next to nothing about bikes so i thought i'd ask my Q's here!

First off, maintenance: how often should i change the engine oil and gearbox oil? and what brand oils do you recommend?

On my cluster i have a temp gauge, is that water temp or is it oil?

My mate reckons they have speed limiters?? doesn't sound right though...

When changing gears, should you use clutch for downshifting? i notice if give it tiny bit of throttle i can get it down gear without clutching, though im unsure if this will damage the tranny over time.

Do you get pulled over much on your sports bike?

My ass cheeks get mega sore after riding for more than half an hour, will this go away after i get used to it? (i fukin hope so lol)

Can speed cameras still get you even though theres no plate on the front?

I probably could have googled all of this but im a lazy kunt and i figured these questions may not have been covered on this forum yet.

Any input will be much appreciated!