Yeah thats how you fill it up,ideally you want the Oil to be about 4mm beneath the hole but dont worry about it,i just fill it up untill it comes back out They take 3.2ltrs by the way
I dont know where else it could be leaking from.Knocking the shafts out by going over a pot hole is unlikley but still a possibility..You can tap these back in but it may be the split pin's at the end are worn and need replaced.They hold the shafts in.Think they cost 18p from Ford as i had to get some the other week because my driveshafts kept popping out