I am friends with a breeder of iggies. She races them, they are not quite as fragile as some would believe. Hers all run with a large pack of dogs, and from what I have seen they boss the whippets and sheltie around lol.
They are VERY cold sensitive, even in nice weather they often need a light coat.
I can't help you with the housebreaking issue, that convo has never came up.