1995 Townace 2.2 TD, looking at buying one, so a few newbie questions!

Hello all,

I am looking at buying a 1995 Townace 2.2 TD auto this weekend, i am in the UK and don't know much about these vans. I wanted to take some engine oil with me, in case it needs topping up. What is the recommended viscosity? And any specific recommendations?
Also any obvious things to look out for when checking it before buying?
Known issues are:
Speedometer not working.
To move the gear shifter from park to drive, the small button needs to be pressed, it doesn't work just by holding the brake pedal.
It will probably need a cambelt change, is that expensive?
Do they suffer from rust? Any known points to look at?

I'm sure i'll have plenty of questions if i do buy it, so thank you in advance for any help received.

Andy