How do I tape and spackle a drywall and plaster corner?

Hi, I have lots of questions so I will give you the backstory. In our front foyer of a 90+ yr old house we had wallpaper all around. I successfully peeled it off 3 of the walls, which were plaster, and the fourth turned out to be drywall (under >4layers of wallpaper). So the wallpaper took the paper off the sheetrock so it needed to come down. After putting new sheetrock up, there are gaps due to unsquare walls in the corners abutting the plaster walls. There are also gaps up to 1/4″ in some of the sheetrock joints due to poor measurement.

Questions:
1. How do you recommend handling the drywall/plaseter corners with gaps between them at points?

2. For bigger gaps, is spackling paste better than joint cmpd?

3. At what point should the door moulding be put back in place? Before or after joint cmpd?

Thanks so much!

Hello,
Thank you for visiting our site. Sorry for the late response but I will help you through all of your questions.

Anything greater than a 1/4 of a gap buy a product called durabond and place it in the gaps to eliminate them. It is stronger than typical mudd and is used to span up to 1/2 gaps. You can always put in a filler piece for gaps greater than that.
Finally you will want add door moulding last after compound.