Before my 2.0T I had a 1.6, and I thought seriously about doing the things you're considering. Tbh it's a total waste of time. You're looking at a max of 15bhp or so from all the mods you do and it'll still probably never be the car you want it to be.
Short of adding forced induction (which will be pricey once you've got the kit, strengthened the internals and your gearbox sorted) there's nothing you can do that will make your car significantly faster.
Do yourself a favour - save the money for the car you really want. That's what I did and I'm so glad I did too