Welcome to OA mate.
You'll find everything you're after here
We all worry about the warranty, but there's lots of things you can do that won't void it. I started off the same way, but now my CDTi is getting more and more modded every month lol.
To look at a heavily modded SRi-T i guess you can't go past Nemo's in the Members section
http://www.opelaus.com/forum/showthread.php?t=13818