I'm looking at the PSE Stinger X bow to get back into bowhunting with and I have been wondering which draw weight I should get 50lbs or 60lbs. I hunt in a colder area
so after a couple of hours the 50lbs draw might be nice, but how much performance loss will I get from that choice? Most shots will be under 30 yards. With carbon arrows will I still get a fairly flat shots? Also not as young as I was with my old Barret compond from 1984.

I assume you are an average adult male? I'd go with a 60# one, you can back it off to 50 to start out if you like. Any recent compound at 50-60# is more than enough for deer. You will find compounds have changed dramatically from 1984. You will not find drop to be an issue at 30yds. Most use multi-pin sights anyways.

Go to a bow shop or Cabelas and have them fit you and tune your bow for you.  They can also custom cut your arrows.

Go as high #'s as you can stand and you will quickly get stronger with practice.  In a few months it will be easy.