Northern Pine Snakes

I purchased a pair of Northern Pines Snakes at a reptile show a few weeks ago. This is a new species for me... so I have a few questions.

The guy I bought them from said that they were eating f/t juv mice. I am doubting that since I've tried to feed them a couple of times now. They would push the f/t mouse but wouldn't eat it. I even tried a fresh killed mouse and no luck there either. Today I tried a couple live juv mouse and both of them ate them. I would rather they ate the f/t or a fresh killed... how do I switch them over?

The male made this awful hissing sound today when I opened his cage... it was a little unnerving. He has always vibrated his tail but the hissing is new. He didn't strike at me but I was really unsure if he would or not. Is this a normal thing for pines?

Can I keep the male and female in the same cage? Since most of my experience is with kings I have kept them apart but would like to co-habitate them if possible for space saving reasons.

Any other helpful info on these guys would be appreciated. The plan is to incorporate them into my wildlife programs... maybe breed them down the road sometime... both are supposed to be het for albino.

Thanks