Campbell's versus indian runners

Hi I've decided to hatch some ducks, I'm hoping we'll get at least 2 from a clutch of 6 but I know these things aren't guaranteed! I thought I'd decided on runner ducks but I'm not sure again. They'll have to be in an enclosed run, I see several foxes a day passing through my garden. The garden slopes away from the house so would have a small pond at the bottom, the run will be 3x4m for 2-3 ducks, (if that's sufficient).
I'm hoping to attach it to the existing chicken shed and run (I've 1 hen and 3 bantams) so they'd have plenty of indoor housing, and use of the other run although it's not as big. I'd eventually like to sort a portable run so I can give them access to other parts of the garden but that won't be for awhile. The breed needs to be friendly as I have a 1, nearly 5 & 7 yr old. I'm also going to make use of vertical space for the chickens which should generate more floor area. Think I'm rambling now I've been reading non stop about ducks for weeks and want to make a decision and get cracking!! Any advice welcomed

Thanks Norfolkgrey, I'll do that, I've just read so much conflicting info on temperaments etc I l
Do you think the setup/space will be okay for 2-3 ducks? Thanks 

LOL. Sassy I am worried about your drake. I have never had any fuss about the chickens. Poor chickens - sorry I still can't help chuckling. Ducks can peck at you but it won't do anything as they don't seem to realise their bills are rounded and rubbery 

Is the duck run separate to the duck run? The size IMO is fine but as said it will become disgusting, however the chickens won't appreciate it much.