It's never easy to try and get everything perfect, but you'll get there
I'm looking forward to some progress pictures and hope you'll have it ready for summer - mine just got the summer tires on!
Excuse my late answer, I've been off the forum for a while!
GTi runs well on 14s, no problem whatsoever (tyre size in my case is 185/55/14).
No spacers needed for Starlites
5w40 will be fine.
As said, once you change the coilpack and all the leads / plugs you should be fine. I went with OEM coilpack and leads, and NGK plugs, never misses a beat!
Also, bienvenido