Your landlord sounds pretty dismissive, I've never heard of a landlord just laughing off a mouse infestation. It hurts their property too. Bat poop causes serious problems... your in a good position because your renting. MOVE! I would move. Some diseases it cause is histoplasmosis, which is a respiratory disease that affect people with weakened immune system (i.e. young kids). The spores from that histo. fungus becomes airborne. The doctor can do a blood test or skin test to test for histoplasmosis.
Plus their poo (guano) and urine attract roaches (doubley ewww).
You can decontaminate, but the way your landlord handled that mouse confrontation I'd just move and deal with breaking the lease after taking her to the doctor, telling him/her about the bat problem, and documenting everything (maybe statements from the friends about the bat at 4am?). AND calling the health department so the next tenant doesn't have to deal with that. For me it'd be the next straw but I still wouldn't want someone else moving into that mess.
Wow, with what Keith A said, you got 2 big health problems with the bat and mouse poop. Move out babe, protect you and yours!