Get someone to help. My wife usually helps me and I use some painting paper to protect cabinet sides while installing. You can do it alone but it's a pain. Or I'm just a big wuss. You can use the blocks to rest the back on. You'll want to get the angle right while installing.

I also use a sparing amount of superlube gel on the parts that touch. With the new parts it will move in and out super smooth.

Yes wife had helped me now a few times. She's pretty good actually and has no interest in pins.

Hard to say the exact angle. I usually have us each grab a side and the playfield is mostly horizontal leaving the front upward slightly. You want the rails on the playfield you replaced to be just above the cabinet nuts. You can then rest the back of playfield on that perch on each side. If you have it right you can move to the front and pull the playfield towards the front to lock in the clips.

This is something that took me a few tries to get right as I don't do it often. It would be great for someone to document the pics of how to do this. I've seen some explanation with pics before but not sure where it was since it was buried in a thread.

If I had pictures I'd share. One of the pros or regulars of doing this will hopefully give a better or easier explanation.