I have an old house that has drywall hung, taped, and finished, but not sealed or painted. I've learned it was hung 8 years ago. It still looks and feels alright, but am wondering if I should replace or can just prime and paint (which I would prefer).

I am going to install T&G on ceiling on 3 season porch I built 20' x 16'. I have the walls done, where wife wanted T&G. I am using a 3" then 4" then 3" then 5" pattern. I will start at the top of the walls which ends in a 5" board. So I will start with a 3" board. Everything is square, I'm kinda anal when building. I have ordered the quantities I need with each board varying in length and all are end matched. I'll start at the house wall, and when each row ends, I want to cut the board ends to match the starting board. This way I don't need to worry about cutting to fit the rafters. I'm guessing I would need to trim the board end at 22.5 degrees I think or is it 45 degrees. I've always done square butt end to the walls before. Is it easier to make the cut on my Dewalt Chop saw or setup a router bit to use on my router table. The latter would save me time changing the saw from 90 to 22.5/45 degrees all the time. Not sure if one would look better than the other. I can put a template board to butt the boards up if I use the saw, so they are all the same. I'm thinking it's a 22.5 degree cut, want to order a router bit and have it ready to go before I start if I go that way. Will be staining, then poly coat before I put the boards up. Maybe someone has done this before and has a better or good idea for me. Thanks for the help, Happy Thanksgiving Day to all greg:)