Valve clearances on a 1997 4 trak TDS


Hello, I need some help with my 97 TDS Fourtrak (DL 52 turbo engine.)
My questions are:-
1. I tried to check the valve clearances this morning but Im not sure where the exact timing mark is on the timing belt cover (I found the mark on the pulley wheel.)
2. Also Im not sure which piston is number 1 (I beleive this is at the front of the engine.)
3. Which is the exhaust and inlet valves (there are three ports on each manifold and the book doesnt say.)

I have a genuine Diahatsu manual but some of it isnt very clear.
Any help would be appreciated.