Didn't read the replies but...I think crating works well for housebreaking. And when they go outside, praise them like they just split the atom. And give treats for going potty outside (and eventually don't give treats every time once they start being consistent). I would not recommend pee pads-I've read articles by experts that say they confuse more than anything. But I've never owned small breed dogs.
As for the leash-they will have to get used to them. A harness might be easier on little ones. Eventually they will quit fighting the leash.