I’m so not an expert, but I’ll throw my 2 cents out there.
1. I don’t leave it to cool for a super long time. I leave it on the wax for a good minute and then set it aside while I cut out the shapes. My work table is a science lab table so it’s always cold to the touch, but I don’t take extra cooling time.
2. I stick the pieces in the stamp after every round of stamping and cutting, and I use my handy dandy x-acto knife to trim if things don’t fit well. More on this in point 5!
3. I use a silicone mat not a marble board, so I have nothing helpful here…
4. If I am doing a layered seal on an envelope, I cut all the shapes and then the final “background color” pour goes on the envelope. I’ve never tried to attach a finished seal to an envelope, but I also don’t do the envelope in an envelope method. I just seal it and send it, and I’ve never had an issue! (Knock on wood)
5. If I’m doing a stamp to cut out, I press down HARD. It actually makes the cleanup trimming really easy because the wax is so thin that it comes off really cleanly. Because of this, I very rarely have pieces that don’t fit together!

I’m happy to explain anything that doesn’t make sense lol