Congrats, welcome!
First off I'd learn to do the servicing yourself. It's mostly pretty easy on skylines to do everything like change oil, oil filter, air filter (or clean a pod filter), spark plugs, brakes etc.
And thanks to the MASSIVE tutorial section on this site, you can learn how to do pretty much ANYTHING for yourself.
Definately wait a little while before you start doing serious mods to the engine, it'll feel amazing and you'll want to cherish every moment as it is hahahaha.
As for body kit mods, that's completely up to you! If you don't like the look, change it. I personally am more of a fan of the R34 S1 front bars too.