The transmission should be an AX-15 - it's easy enough to check, and I think they changed in mid-1989. To confirm, crawl under and look at the transmission case; if it has a longwise split, it's the damn Peugeot, and you'll want to upgrade. If not, it's the AX-15, and that's an acceptable box (I'm on my third Peugeot in my 88, since I bought the thing!)
The oil pressure sensor (for light or gage - the difference is internal) is on the passenger side of the engine block, down by the distributor. The coolant temperature sensor is on the driver's side rear of the cylinder head. These are the two you'll want to replace if you're changing instrument clusters - the wiring for the gages is already in place.
The nose question can be answered with a search - but I can't think of the terms offhand. I'm sure it's been covered here in the last several weeks.
I'd have to crunch some numbers to see if that's a normal "cruise" for you - and make sure you have 3.07 gears (you should) and know what size tyres you have. I typically cruise at 70 in fourth gear, running about 2900 with 3.07's and 30's (I quit using fifth gear - 2500-3000 is ideal cruise for the 4.0, and I actually gained in fuel mileage when I started doing that. I don't use fifth until I get up to around 80-85...)
Welcome aboard!
5-90
