Nice find. Aside from '93-'94, '01-'03s are my favorites.
Engine...any 5W20 is fine in the Duratec 2.3. Not a picky engine.
Trans...stick to ATF, or manual trans fluids intended to replace ATF. Not a super picky trans, but gear oil is a no-no. I just used plain Pennzoil Dex/Merc in mine.
Diff...not picky. I have run 80W90, 75W90, 75W140 and could never tell a difference. I have always sealed these with RTV Ultra Black and never had a leak. It has the old Ford 7.5. I have never had to do anything to a Ford 7.5, even the fluid changes were probably unnecessary.
Coolant...G-05, John Deere CoolgardII are preferable, but again, it's not picky. An '01 may have come with green, but I doubt it on the 2.3L, it was probably G-05. My '01 2.5 Lima came with green.
Plugs...NGK or Denso should work great in that engine. Again though, not picky trucks. It's due for a tuneup in the next 20K miles.
The shift rail plugs are an easy fix. There are three of them at the top of the trans. You can get them from the dealer for a few bucks. If replacing with original rubber plugs, all you need is a screwdriver. Just pop the old ones out and push the new ones in with a little ATF on them to make pushing them in easier. Some people opt to replace them with metal freeze plugs for a permanent fix if they have the trans dropped for a clutch/slave cylinder. There is no way to get metal freeze plugs in without dropping the trans.
Some people remove the factory resonator box thing on the air intake pipe on 2.3s. IIRC, Tallpaul on this board did it with one of those Dorman rubber freeze plugs. Ford eliminated the resonator box sometime later on, so you could just get a later air intake pipe if you can find one. Probably won't see significant gains doing that though. The A/F is the same one used on the V6s, so it flows plenty of air, but there is no shortage of aftermarket intakes for Duratec 2.3s. Name a company and they have one.
If you want to upgrade the exhaust, Dynomax is the way to go. Walker/Dynomax direct fit stuff is really direct fit on Rangers. Other companies make exhaust kits for these trucks, but you really can't go wrong with Dynomax/Walker, especially in FL where it won't rust out. I had a bad experience with a Magnaflow y-pipe on my truck (simply would not fit an automatic trans truck, no way, no how). Dynomax/Walker stuff always seems to fit like a glove on these trucks. Had a Dynomax Super Turbo cat back kit on my old 2.5L Ranger, and a Walker y-pipe on my current one. Totally hassle free installs with perfect fit in both cases.
With shocks, just don't get cheap Monroes. They were leaking oil on my truck in a matter of days. Anything else is fine, including better Monroes (Sensa-Trac on up). I am running Motorcrafts in the front and KYB Excel-Gs in the rear on mine currently and have no complaints.
You really shouldn't encounter many problems at all on a low mileage 2.3L manual trans Southern truck. The only one that comes to mind would be the clutch slave cylinder. It is a pain to replace because you have to drop the trans, but it doesn't always go out. On some trucks the slave cyl goes at 40K miles, on others never. It never had an issue on my '01. Regardless, whenever the clutch is done, the slave cylinder should be replaced as insurance while the trans is out. Other than that, I wouldn't expect much at those miles. 80K is nothing on one of these. They don't have many age related issues...aside from the shift rail plugs, the rubber parts are really durable, and even those are not all that common of a failure. Electrical issues tend to be very minor...switches sticking and the like. Being an '01, it should be a reg cab as you could only get Super Cabs with a V6 that year, so things like the door ajar light staying on won't be an issue. The switch for the parking brake light in mine has started to stick, but it doesn't bother me enough to replace it. The light doesn't always illuminate when I set the brake.
Ball joints may be an issue later on. On mine the boots cracked almost all at the same time around 125K miles. I proactively replaced them as they are sealed from the factory, but the joints were still good. I went with Raybestos Pro replacements and have been very happy with them. I personally haven't seen a Ranger with less than 150K miles that actually had bad ball joints, but I have heard of them going bad before then. The noise will alert you long before they are dangerous. At 80K, they should be fine. Even if the boots are cracked, they probably have a lot of life left. My OCD with my truck's mechanicals just couldn't deal with cracked boots, so they had to go.
It should be an excellent daily driver. If mine were to be wrecked beyond repair tomorrow, I'd have another in the driveway by the end of the day.