whoa. sounds like you have a lot going on. well for starters, glad to hear the lice is gone

. second....rats chew things. if youre previous guys didn't....then you were lucky. i NEVER keep anything within rat-arms reach of their cage, i've gotten my jacket chewed among my cell phone charger cord as well. they're rodents, they chew, just cater to it.
the biting-while-holding probably has nothign to do with their general chewing habits. if you eeep when they nip you, they'll learn it hurts you. my boys mostly lick, but they use their teeth to try to groom me as though i had fur. when i rat bites you and mean it, you'll know, it HURTS and draws blood. so if their nipping isn't like this, then you're fine. they could be letting you know they're tired of being held, or they'd rather run around. plus i've hear that giving treats through the
cage bars, almost trains them to grab anything that comes close. i've made a conscious effort to NEVER, not once, give mine treats this way. i always open their door and stuff. now i'm able to stick my finger through the bars to tickle them, and they dont' try to eat me lol.
with the prego thing....i suggest posting pics of the rats so we can see, it'll help immensly
