If you swap to a 1.6L 8 Valve you can just use the block and head and keep your existing intake, exhaust and wiring. You already have fuel injection so you won't gain much by swapping it over from the Tracker.
If you go to a 1.6L 16 Valve you will need to redo the wiring. There is a really good write-up somewhere on the site for a full wiring conversion, I'll have to see if I can track it down. But no, you don't need to pay Trail Trough for it. But it does make things easier. For the 16v conversion you will need a different fuel pump.