Hi all, Iv'e at last managed to get myself a 7/8 descent standard Jan 91 mk2 gti 8v (oops!)

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I drove it 100mls home this afternoon, it ran sweetly, but as ever on a long journey a few issues not picked up on a short test cropped up which I could do with some confirmation/advice on......
1 When I set off and got on the Mway the temp gauge only just got off the bottom....Thermostat I'm guessing?
2 The heater worked OK when I set off but when I got stuck in some traffic the temp went up to halfway and the heater went cold...I'm guessing that's the old by-pass valve issue?.......or is it just doing its job? The rad fan came on OK just above halfway on the temp gauge.
3 Stopped in services and lifted the bonnet and there was a trickle of steamy water overflowing from the coolant res. but the engine didn't seem particularly roasting and wasn't boiling.....dodgy cap?
4 Tried to chech the temp via the MFA, it works fine but no oil temp reading at all just dashes? I guess this might be the sender but not being used to 8v I'm not sure where it is. I can see 2 on the top of the oil cooler and one on the end of the head.....but which one? Is there a way of checking by connecting to another sender like on a 16v?
5 The knock sensor wire has chafed through its outer cover on the oil cooler.....it seems to be a coaxial screened wire, is this fixable or am I in for a new sensor?
6 The wheels are BBS RA, I think?? There is no 'lip' on the rims though, they're tidy but the rims are flush right up to the tyres. Is that a refurb thing or is it because its a late model or maybe off a non VW? Not like my previous RA's anyway.
7 It has a roof aeriel and a grommet in the wing, and smoked back lights.......I thought that was a 16v only thing?
I have some other questions but I'll wade though the 'search' with those as they're less pressing
Thanks in advance. J