There are a couple of good stickies at the top of the forum you should read through. Lots of good info.
As far as parts go, almost all of the aftermarket rods and pistons are decent. One of the more common combo's would be Eagle rods (cheap and good) and a lower compression piston like Ross. You shouldn't worry about bearing sizes etc unless you're overboring those as well. Any place that sells them for the KA will have the correct ones. The measurements are in the FSM, which is in one of those stickies, I believe the FAQ.
There are tons of choices when it comes to turbo selection and tuning methods. The main obstacle being cost. Before you go buying any turbo items, run them by us first. There are some pretty shady EBay items you'll want to stay away from.
Welcome to Nico
WD