Welcome to the addiction.
As littlebeast said, check it every fill up. Several members have blown their engines, later finding out that it was out of oil. I feel lucky in that I don't lose oil, and I'm at 105k. For whatever reason, members either don't lose oil, or lose about the amount you're presently using. It doesn't otherwise seem to lose any performance or longevity, just keep an eye on it. Also, our PCV's tend to get plugged, and some claim that keeping these clean can help with the oil consumption. Others have installed breathers, though others say that's not a good idea. Use the search feature to find out more.
Once you get the plastic screw from merlin, get a dowel and glue segments in all four of the screws, and you'll never need another one.
I wouldn't worry about the missing illuminated D. When you change out the speedo, replace the bulb.
On this site, there is downloads of the full service manuals.
Your headlight had a run-in of with a stone tossed by a vehicle.
Marlin (yes, different from Merlin) likes to scour junk yards, he'd probably be able to source a mirror. I think these were the same as Rodeos. Troopers came with chrome versions of the same mirror. I'd probably talk to Merlin (VX knowledgable Isuzu dealer parts counter man), when you are getting some other parts, and ask him the compatible models and years.
JDM parts are really hard to find from what I can tell. I'd contact crotchrocket or petros, as they are active members abroad, and they certainly would know where to go. Ask them to get me a JDM fender mirror for me while you're at it. See what you can do, but worst case scenario I could probably help you out setting the type. You could then have it printed at a service bureau to film. You would either get clear on black, or black on clear. You could layer the black on clear film over a translucent white piece of plastic. The red and blue dots could be created as well, just matters how carried away you want to get with it. I've got an '01, so I have climate controls, and would need exact measurements to recreate this.
And you put a Toyota VX on an Isuzu? tsk. tsk. tsk.
'01 Kaiser SC'ed VX #0867