I'll tackle some of the questions and leave the rest for the other old farts. (Hey, the Old Farts Vert Rollerskating Club. Sounds good.)
Your boots may stretch a little bit with use so you can get a few more miles with them. Yes you can get your plates remounted on a new set of boots. Check out the pro shops of roller rinks in your area. With the recent upsurge in jamskating low cut speed boots are very popular. Probably best to replace the cushions and pivot cups after all these years. Rubber dries out and cracks with age. Are those Sure-Grip Magnum plates?
The question of wider trucks I'll leave up to you. I'd say stay with what you've got for a while till your legs are back in the groove. It takes 3 or 4 sessions to feel normal on your skates again. Spend your time doing drills (crossovers, mohawk turns, skating backwards, etc.) to get the various muscles back in gear. Long distance work just makes your legs rubbery and really doesn't contribute much to skill. The moves will all come back to you.