ACERBIS GAS TANK 3.4 GALLONS - NATURAL

Yes, your stock seat will work just fine and your kickstarter will remain in it's place without a problem. As for the radiator fan however, I honestly cannot say whether or not that will work for your bike with this tank (as that is a bike specific issue). I certainly don't see any reason as to why this tank would interfere with the space occupied by a radiator fan, but I'd probably recommend jumping on KTM-talk's website just to see if anybody else has posted a thread regarding this being an issue for your specific model. So if you get a chance, I'd personally recommend just setting up a KTM-talk account online at http://ktmtalk.com (if you aren't already setup there) and simply checking to see if anything has been mentioned about this being a problem in the past......