I am finding the the T5 in my car is stiff to shift when I am accelerating hard. How does putting in a shifter make it easier? What parts are really replaced?

 

Shifter won't likely fix this, unless the bushings are worn and the arm itself is binding. More likely the clutch isn't fully releasing. Bleed the hydraulics and see if that doesn't clear it up.

As for the last part of your post, based on the questions you're asking I'd say not much will be easy for you. Get a manual.