err, err, pass :D
just go for whichever one you can get cheapest, not really looked into it but I'd imagine the 1.8 Focus was more common than the 1.7 Puma so the comsumables for the focus may be more readily available/cheaper????
the cam moves independantly from the pulley in an anticlockwise direction but as far as I know there shouldn't be any movement away from/ towards the engine - I am prepared to be corrected though
to time it up you need a timing pin that goes into the blanking bolt you've found, when the crank...