The new stem I ordered came in at Ada Bike yesterday and I was so anxious to get it on that I got working on the replacement right away. The old stem is a closed-front type, so I had a decision to make: do it the quick and dirty way, bending the old stem apart, destroying it, or do it the right way, removing the brake levers, tape, and accessories from the handlebar and sliding the handlebar out. Quick and dirty might have been easier, and would have saved me the cost of new handlebar tape, but destroying an otherwise perfectly good piece of hardware for expediency isn't in my nature, so I decided to do it the right way afterall.
I did some Internet research on how to replace a quill stem, and then some more research on what to do when the old stem is corroded in place: loosen the bolt until it's half an inch out, then whack it with a hammer through a piece of wood, then apply muscle to twist the stem out. This eventually worked. The stem turned out not to be stuck quite as badly as my seatpost.
Step by step, with deliberation and research, I finished the project today, save for re-taping the handlebars. I did watch numerous Youtube videos on that subject, and was surprised to learn how many different ways there are to do it, but before I commit this final step, I want to take a couple of rides to make sure I'm happy with the position of the brake levers.
I still haven't gotten my derailleur hanger repaired, or replaced the rear derailleur, the chain, and the gear cassette. Based on the enjoyment and success I had with the stem replacement, I am thinking of doing all but the derailleur hanger myself, and hopefully I can time the repair with the bike shop so that I will miss a minimum number of riding days and still have my bike available to bring up north to Farm Fest next weekend.