zebra loach

So, i want to get some sort of fish that is a bottom dweller for my 29 gallon. the question is, should i get cories or zebra/kuhli loaches? I really like both, but would the loaches hurt my 2 african dwarf frogs? Any feedback is welcome, thanks!:-D

Right now I have 3 cardinal tetras, 1 sailfin molly, 1 zebra loach, and 2 clown loaches. My zebra loach is always chasing my two clown loaches whenever they eat and dig into the rocks. He also nips at them sometimes. I've heard that loaches like to be in groups and like to hide. I was thinking...

I have 2 clown loaches and one zebra loach. All three of them like to hide behind the heater in the corner of the tank. Is that normal? Also whenever someone walks by the tank they swim back to that corner to where the heater is. Is it normal for them to get startled like that? And I noticed...

I just got a Zebra Loach and 2 Clown loaches and 3 cardinal tetras a couple days ago. And one other fish but I forget the name. I was wondering if I should get another zebra loach so he won't be the only one in there. Also I was wondering if I should get some sort of cave that the zebra loach...