Tint cannot be installed backward... Well... . I guess it can, but it will soon fall off the window as soon as the water evaporates.
Besides, tint has an adhesive side.
Be sorta like wrapping christmas presents... . using the tape sticky side out.
Yes tint increases reflection. That is the whole idea of installing tint in the first place. Unfortunately this ends up being a side effect on the inside as well.
Darker tints reflect more light, hence more reflection. The plus side is that you aren't letting as much light inside to begin with... so it may equal itself out.
As the tint ages, the amount of reflection will decrease somewhat.
I'm assuming you know not to use Windex on tint? or anything with ammonia. Ever see a car with Purple tint???? Well, they didn't install it that way, thats what happens when you clean tint with an ammonia based product.
Make sure the product states "safe for tint". And forget using newspaper. .
FWIW: You'll never get pulled over for 35% tint on the side windows, nor do I know anyone who had trouble at PA inspection time...
20%..... depends upon the officer... and whether he had a fresh donut that morning. .