"Crimp fix" is a quick, easy thing every single Max owner should do. There's a good tutorial with pictures on Vmaxoutlaw.com. The max tends to have a pretty low voltage, one crimp before the R/R in the harness is a big cause of it. My Max never had issues with the battery going dead or slow cranking, but when I checked I only got 12.9-13V with the engine revved off idle. After the crimp fix, that went up to a more reasonable 13.6-13.8. Still a bit low, but entirely acceptable and never had any battery/power issues.
To check the head bearings. Put the bike on the centerstand, then have a helper(or a jack) lift the front wheel off the ground. Put the handlebars in the center, and give them a little push. They should fall and hit the stop, but NOT bounce. If they bounce, the head is too loose- a big cause of high-speed wobble. There's lots of threads here about how to tighten them, including some on the "furbur fix" (search it), but some people have mixed feelings about that fix's effectiveness.
Mods? Best bang-for-buck is a jet kit. You've got a few options there. Morley's kit is popular and has good reviews, but I have the Dynojet stage 1 and have no complaints either. Stage 7 is really more for the strip than street. You'll run rich at pretty much anything other than WOT, your idle will suck, and you'll chug gas like nobody's business. Significant power gain, but at the expense of driveability.
I'd strongly recommend a Venture rear diff conversion, it's geared higher so you turn about 400 RPM less on the highway. With a Dynojet kit and Venture drive, I'll see 42-43mpg at a 75mph cruise- great by Max standards.
T-boost is a fun gimmick, but I rarely ever use it. Setting it to open at 3k instead of 6k gives a little more torque down low and seems to make the bike a bit more responsive on the highway, but kills mileage....get mid to high 20's running with it open all the time.
I have the ebay "nicetect" chinese rear shocks on mine. Honestly they're not bad. Yes, they're a bit soft, but they give a very smooth, soft ride on the highway. I only bottomed them once, and that was on an absolute whammy of a pothole that almost sent me over the handlebars. Otherwise, no complaints. Got several thousand miles on them with no issues.
I have a complete front brake system from an R1 on mine....brakes are no longer any issue. Phenomenal power, far beyond stock. But SS lines are a great upgrade to the stock system and get rid of the "mushy" feel from long rubber lines. Plus, not that expensive.
Tires? You'll have to see how well whatever you have hooks up. Avoid Avon tires like the plague. I have a Venom X on the back of my bike and it's absolute garbage. No traction, doesn't track well, and it's an absolute nightmare in the rain. I mean, it's downright scary in wet conditions. I can keep it lit up off the line to over 80mph. The Max is powerful, but that's just ridiculous. Lots of people here suggest Shinko Tour Masters, due to their good quality, high traction, and low cost. Think I'll go with those this spring.
If you're concerned about reliability, you might want to do the shift segment update. Pre-99 models have the "old" shift segment that tends to crap out without notice. The pins fall out of it, and you lose the ability to shift. On old styles the pins are just held in with a very thin, flexible "finger". New style units integrate the pins to the actual drum, so they can't fall out. It's an easy job, and takes maybe $100 of parts(at dealer prices). Pull clutch cover, remove clutch basket, and it's right there. One screw and it pops out. Put the new one in the same way, re-assemble.