I finished the OFHG a month ago and it was a pain. The gasket had become brittle and didn't come out as a single piece. I had to use a pick as others have described. Be careful if you have to use a pick. I envisioned a piece of the brittle gasket flying off and going into one of the oil passages on the side of the engine. Luckily I covered up the oil passages because sure enough a few minutes later a piece came flying off and bounced off some crumped towels I had covering the hole. Remember to take your time and make sure you have the proper tools and all your parts in advance.
As far as doing other preventative maintenance tasks, there are a bunch that could be done. Other have already posted a lot of them. You have to consider your budget though. If you had the funds, I would suggest doing as many as possible. Your car will be rock solid for miles to come. But if you simply don't have the funds, pick and choose your battles. I would definitely suggest cooling items like expansion tank, water pump, upper and lower radiator hoses, and themostat in that order. Good luck.