If you can do a clutch on a multipla you can do any job on it, you are now fully qualified!
I did my cambelt recently, didnt change the water pump as many do, in fact I've changed 3 cambelts on multis and never changed the waterpump, never had a problem, yet..
Changing the water pump just makes it harder, I think you may need to remove the camshaft sprocket?
Anyway for the cambelt, used tippex, but have always found finding any sort of markings on the crank vague, so just use tippex on the old belt and dont move anything...but theres loads of info and some usefull pictures on this forum.
You may need some special tools like ribe to remove the engine mounting on the cambelt end, but removing the aux belt is easy, just by wrenching the tensioner back manually on its bolt head.
Good luck!