Great first post! Ya done good!
About the best advice is to connect up to the airheads group and attend a tech day - more of a social get-together, but if you've got questions, that's the place to find answers. Those guys will be able to tell you in short order what's up, what to worry about and what's normal.
The squeaking turn signals is most likely caused by the turn signal beeper barely working. For a few years they thought it was a good idea to have an audible beep when the signals are on - not sure why. Perhaps they thought the rider would hear the beeping to remind him to turn them off. Doesn't work - I know guys who rode for miles with their signals still on. And beeping.
The clunk in the front end is most likely that the bumpers disintigrated - a rubber donut that softens the collision of slider and fork tube. Does it make the clunk on compression or rebound?
Steering head bearings are probably ok. You don't need to remove any front end stuff to check them. It's easy, and one of those things that will take two minutes for someone to show you how to check them. Essentially, they need to be loose enough to move freely, yet with no slop. Just a slight bit of preload is needed. The grease can get old and stiff and make the bearings feel notchy, and you'd swear the bearings are bad. But all that's needed is a clean up and fresh grease. The handle bars should slowly fall over to full lock on their own when the wheel is started in that direction. But the problem is there's wiring and cables to muddy the issue. One side usually falls easier than the other.