Picked up a nice used driver's door glass to replace my scratched original.

Any tips to make this easier? The used piece has the old HW attached to the glass. I'm guessing this all needs to come off 1st.

Any reason the alignment would change?

I can change a bit. My best advice is to remove and re-install the old glass a few times until you are comfortable with putting it in without scratching it. I use cardboard and thick towels to reduce the chance of scratching the replacement.

Be gentle removing and replacing the old hardware. It is easy to break. I also lubed up the wear points and tracks with synthetic disc brake caliper grease. It won't attack plastic and has all kinds of good slippery stuff in it. I use it on a lots of things these days. Great product!

How are your door hinges, and door and glass seals and wiskers? It's nice if your seals are in great shape and your doors are adjusted and lined up nicely when it comes time to do the fine adjustment on the door glass. These cars have enough wind noise at the glass as it is. Improper door and glass adjustment only makes it worse.