what exactly do you guys mean by pushing yourself? i really cant imagine how i would do that 



and a used KT100 engine. Actually my budget is very limit and racing in China is not cheaper than racing in US so I can only buy some used engine and chassis. In my opinion KT100 is a good engine to start, but I don't know if it is available in America. 

Well I would estimate across the USA there must be 20-30 sprint kart classes. All with their own selling points. The reality is each track will have it's popuar classes so that's what you need to find. I gave you some links earlier. Those sites have links to forums with people that are more in tune with what's raced in your area
The difference between a CIKFIA suit and an FIA suit are that CIK suits are not fire proof but skin proof whereas FIA suits are the opposite 


:razz
Do NOT buy anything. For all you know your local track might not run Rotax karts and you'd be stuck with a useless lump of metal. Rotax is strong in Canada, but it doesn't mean it's strong everywhere else.

