You do seem to have found the worse arosa ever!
My 1.0 has had a few problems, but they were mainly down to the
dealer not having a clue what an engine is, never mind
how to go about fixing one!
TBH the 1.0s ARE the most reliable out of the petrol Arosas, the 1.4 petrols, mainly the sport, can be trouble as the miles creep up. Things like pedal boxes (sounds like the one you tried was failing) can fail, which can wear the clutch as it fails, then it will snap and leave you with no clutch pedal. The 1.4 can also be bad for engine wear and gearbox issues!
HOWEVER, dont let that put you off, if you find a good one you should be fine with it. Although i would say if your set on a 1.4 make sure the clutch is light, a heavy clutch will put more strain through the pedal box and risk it going.
Ive heard of very very very few 1.0s having that
problem, their gearboxes last as do the engines. I have seen 1.0s with well over 150K for sale. One i saw a few months ago was an 04 reg 1.0S Arosa with 145K miles! So obviously a lot of motorway mileage in that time.
1.0s are ok on the motorway, they do pull quite well once your up to speed, they can sit at 90 if you really want, but the engine is reving quite high then. Most comfortable around 60-70.
Tdis are a fantastic engine, well suited to the Arosa, with plenty of power on tap and low running costs too.
You should be able to find a good one, my little 1.0 drives like a dream, i still love driving it, even after having it over 4 years now.