a 90's 200ish cc isn't going to have much power to begin with.

> It is tough to start from cold

Do a valve check and make sure they're in spec.

> After riding it around, it seems like the idle is really high

Check for vacuum leaks around the carb and intakes, rubber and metal can expand after heating up. Buy a can of carb cleaner and spray around the carb and intake while the bike is running- if you get sudden dips in RPM's while spraying you most likely have a vacuum leak.

> How will i know if the clutch is going bad or needs replacing?

At a low speed put the bike into 3rd gear and give it gas, if it shakes and stutters your clutch is probably good, but if the engine rpm's increase without your speeding equally increasing then your clutch may be slipping. Before digging into your case though make sure your clutch cable is properly adjusted and lubricated. You want a little bit of slack in the line when the handlebars are fully turned in both directions.

> My chain looks old and was very dry, thinking i want to change it just to be safe.

Change it asap before it snaps and busts open your engine case or leg.

>How to figure what chain and sprockets i need?

Use Bike Bandit to find part numbers, although there's probably a ton of aftermarket sprockets and chains that will work just fine.