I WANT TO CHANGE MY STOCK 15s TO NEW WHEELS, IS IT A SIMPLE MATTER OF BOLTING ON NEW?

 

Yes.

 

If you get the same bolt pattern and offset there will be no problem?

 

Well, You need to make sure you get something with the same bolt pattern, and a similar offset.

The 5-lug offset is 5x114.3, and I believe (but am not sure) the 4-lug is 4x110 (it could be 4x114.3, though)

Stock offset is about +40; I'm using wheels with a +38 offset, and they are great.

Oh, and if you're going to put on larger than stock tires, make sure you're not going to have any rubbing.

Here is my personal setup, which I think is nice and sporty for an n/a, without making it less of a daily driver:
Wheels:
17x7
bolt pattern: 5x114.3

Front tires:
215x45r17

rear tires:
235x45r17

Oh, and if you use the "search" function of the 2nd gen forums/archives, you'll find a lot more good stuff.