Most guys have overinflated issues with a car they have never owned. Let me address some of the things people didn't bring up important for all of the 911's from those years.
The most important thing you need to look at is the engine block itself, these car do use alot of oil and as a result an abnormal consumption rate will mask problems for a first time owner like yourself. On the early cars there was a small intermix and/or cracked cylinder issues with the 3.4L engines, depending on where you buy the car it should have already been taken care of.
Do not bother with a leak down test if the car is as low mileage as you say; if the linings were indeed cracked these engines like to make a hell of alot of noise. The problem with this particular motor is that the car will smoke and misfire regardless of if there is coolant in the car when a problem is present. You cannot assess a cracked block with a leakdown test because cracked blocks with damage near to the core plug are not inside of the cylinder. If the car has either problem it is safe to assume you do not need to do a leakdown because the problems have already gotten to a point were it is cost prohibitive to buy an abused model over another. This is your major concern if you do not buy the car from an enthusiast.
You will hear alot about RMS, I am sure you saw this on rennlist. The Rear Main Seal can fail on any Porsche within these years, I see it as a nuisance - others make a big fuss about nothing. If you look on the underside of the case and see anything leaking automatically assume you need to do some sort of RMS repair, if it is leaking to the floor do a complete RMS repair without thinking twice. Why? Well if your RMS is broken you will want it fixed, but if it is your intermediate shaft that is leaking you need that bitch fixed now. It is much more serious to have a leak here and will cost more money, especially if you let the problem get worse. An RMS leak ruins the seal preventing it from holding a seal again, and eventually leads to something big, or expensive, needing to be replaced.
If the oil consumption issues are bad enough it means your IMS and RMS have failed, if your are going to take out the transmission you might as well change the clutch too. Most people will not do this unless the car is losing alot of oil and hold off on the repair until it is a little worse. I don't have issues with someone doing this, but I feel it should be fixed the right way if you know there is a problem.
Be safe and ask if the RMS was repaired as soon as you check out a car, you will let the dealer know that you are well aware of the possibility the RMS will cause further engine maladies.
The coolant tank likes to split, and it leaks slowly, because of the nature of how the tank leaks it is usually too far gone to repair once you find a leak. You will need a new coolant tank in this case, it's a fairly common thing to find. I charge around $500 to put a new coolant tank in. Speaking of which Porsche also issued a new coolant tank cap that you should spring for to avoid any other simple problems from snowballing. Check the oil for coolant and the coolant for oil, this is covered under a service warranty if you do find there is a leak.
Off the top of my head you should allocate $500-$1000 for repairs or upkeep related to your front bushings wearing out or a creaking front suspension. This is not a repair issue to me as it is more of an upkeep matter, but it makes a really annoying little crunching noise and you will want to get it fixed.
One last thing, if you have a water pump leak, or suspect any problems with it's associated hardware, run away. Manbearpig is coming, and he wants your wallet. Everything else is either an upkeep issue, or very unlikely to happen to you. If you ask me though, an older Porsche is what you really want.:angel: