I suppose you have to consider how often you would be in 4x4 mode, your driving conditions, etc... When I bought my Explorer, well used, it already had manual hubs, and at that time I regularly drove early mornings on unplowed roads, so I just wanted 4x4 mode all the time no matter what. So, I'm a fan of manual hubs, I like turning a mechanical thing and knowing for sure it's going to do what I expect it to do. My case may be exceptional.
I will say, if and when you go to manual hubs, you might as well rebuild the spindles, do the brakes, and take a critical look at ball joints, tie rod ends, etc... which is quite a bit of work, but good to get out of the way.
Gotchas... there are black cube relays in the under-hood power distribution box. They fail. If the PCM or fuel pump relay fails, you are dead on the road, though you could swap in the blower relay and shiver your way to the parts store. I would just buy a new one now and throw it in the glovebox. It would not be money wasted.
I would visit the threads on cracked fans and fire hazard from debris in the blower/resistor compartments.
Chances are, there are still some grease fittings in the front end, and quick-lube shops never bother with them. You should... they are probably dry.
The ABS on the first generation is an early design, and for me caused some unexpected behavior. I ultimately disabled it, but again, I was driving regularly on difficult snow and ice. Do not lean on the ABS too much, drive like you don't have it.
Upgrades... if and when your alternator goes out, swap in the stronger 130A alternator. The lower 90A is just barely enough in my experience.
Headlight housings are cheap. If you have foggy pitted lenses, this is an easy upgrade. And, the way the headlights are powered is not ideal. That is, the power path is long through barely adequate wiring through the headlight and hi/low switches, and finally to the headlights. That's voltage drop. There are add-on harnesses that shorten that path, and use relays to get the most power possible to the bulbs. If you do mostly city driving, not a big deal. If you share the road with deer, this will be a bigger deal.
Front bumpers are surprisingly cheap, around $100. If yours is rusty or bent, this along with new headlight housings will really bring your front visual back to life.
Tools and stuff... I would budget in the following items:
- Factory EVTM wiring manual, cheap on eBay
- Fuel Pressure gauge
- OBD I scanner
- A good quality grease gun, if you can find one. Otherwise, whatever you can find. They are mostly junk these days.
I feel like I am missing things, but that's what I could come up with this moment. Welcome to the forum!