You probably mean RX not RS...
There are minor problems to look for but they really are minor. The bike you want for as super cheap as they are now may take a little maintenance. Search this forum.
A quick check of E-bay for whatever parts you're scared about will tell you how much and how easy they are to get.

JT sprockets for the 43-44 tooth conversion you should do ($30 and the OE chain fits) and many more aftermarket available. The front cush drive sprocket is still available from both EBR (still in business BTW) and LAP.

Brake disks are the same dimension as every Buell since 2003. You have a 5mm or 6mm choice from EBR. EBC and others make replacements if you don't want OEM. Pads for the ZTL-2 are available from everyone. A good street pad is the HH from EBC.