I've wanted a vw camper since I was at school and this weekend I've finally got one

It's an 89' T25. Bodywork and underside are not bad and the interior is tidy. It's had a 1.9td lump fitted and a 5 speed box. It does have engine fuel trouble and after driving 6 miles it conked out and had to be towed home. (The guy I bought it off did tell me it would conk out at some point.)
First couple of questions:
How do I know what engine is fitted? There's no code stamped between cylinders 3-4 on the block, but there is a large H in this place. There is some numbers on the block near to cylinder 1 but are not one of the recognised codes.
Has anybody had similar problems and is the fuel problem a common fault/quick fix? I can see that the 'balloon' style hand pump on the fuel line is sucked in when the van is running.
There is a oil leak where the dipstick tube meets the engine when it is running. I'm going to check oil level when it stops raining but I think there may be a seal missing.
I'm going to be doing lots of work so I'll update on progress.
Thanks in advance for any replies/info and hopefully I will bump into some of you next summer