New to 200 TDi belt change and oil leak

HI
I Am new to this engine and i cannot understand the books. 2 questions: if the engine has no flywheel fitted how to i time it to change the cam belt- there are marks on the cam pulley and secondly; Does this look like oil from the crank front oil seal which should be replaced?
thanks.

Arrow cast into cam belt housing, clean up the area above the crank pulley directly in line with the crankshaft keyway and you will see it.

Pic stolen from the web,

There is also the timing pin( I think a 9.5mm drill is sometimes used) in the injector pump pulley seen in the pic, good idea to replace both the crank and cam seals as you’re in there with good quality ones