haha no prob...
Weeeellll... a few things:
- check for rust below rear window on the boot (builds up in the seal)
- make sure there is no smoke from the exhaust, give it a good rev.. blue indicating worn valve stem seals or possibly turbo on its way out, black meaning overfuelling as you prob know - dont worry so much if you get that
- No engine lights or TCS light constantly on
- Brembos are a very expensive upgrade for standard cupras so big bonus if you get one with (standard with cupra R)
- Check the usual oil levels & colors (the engines are prone to sludge more than others if not properly serviced)
- Good service history (reason above & the usual benefit), if modded really should have more frequent oil changes.
- Most are modded with a map, nice cooler & a few other bits and bobs...will save you alot of money in the long run if you can afford the insurance
- Mileage isnt a massive issue, there are cupras on 150k+ still going.
- aim to get one before 2002 for tax reasons
The bible with these cars is VAGCOM, the engine is fairly advanced so any sort of issues at all will be brought up, just check the faults...although if any are showing they may not be as dramatic as whats shown (e.g. when i first bought my cupra i got alex to plug in VAGCOM, it came up with 13 faults, alex then went on saying i'd made a big mistake listing how my turbo & engine was completely fooked - turned out to be a sensor cable had degraded shorting on the engine making the ecu freak out
p.s. dont believe a word alex perkins says especially when its not a polo...ask a trained mechanic 
)
Engines & gearbox are pretty much bullet proof so you dont have to worry too much about that!
Common issues are all fairly simple & cheap
- Coilpacks blow causing lumpy idle & power loss £30 from dealer
- MAF sensors go (mainly on modded cupras because of increased air flow), another cheap fix £60ish for a new one
- Window regulators (same as gti)
- Interior door handles are the same as the gti, so expect them all to look scruffy
- ECU is susceptable to water damage as standard, difficult to diagnose (get this sorted when youve got it)
- plastic waterpump fails (upgrade to metal pump on 60k service) - make sure thats done if 60k+
- few others but not important when buying...
Cupra R is cool to have I reckon as there are only 75 in the uk, but you will be paying extra, and the only differences are:
- badges
- handbrake has red stitching
- steering wheel has red stitching
- cool gear nob
- map to 180bhp rather than 150
- brembos
- half leathers have seat sport badges
- OZ 16" multispokes
(think thats it)
Good luck on your search, try SCN for sale section first as they will be most likely cared for...
If you need any more help dont hesitate to ask, or pm me