Applying to VS after Insight scheme rejection

Absolutely. The converse is true, I have gotten through the first year schemes for some, and then the vacation schemes. I have also gotten some schemes, and was rejected for the VS prior to the interview!
 
Yes, you should be fine. The only fairly solid rule is that if you do a vac scheme at a firm but are unable to convert it to a TC, then you can't reapply. Other than that, not really a problem.