1. Depends on whether you're breeding for feeders or whether you are breeding pets who occasionally become feeders. If you're just breeding for feeders, putting a group of five-week-old female mice together with a five-week-old male may well produce litters by the time they're eight or nine weeks old. If you're breeding for pets who also occasionally become feeders, most mousey people recommend you don't introduce male to females until they're eight weeks old.
2. 19 to 21 days, give or take.
3. A female mouse CAN and WILL breed immediately after giving birth - they go into oestrus within a couple of hours, and if there's a male in the cage, they will certainly have back to back pregnancies. This is hard on the female, however - particularly if you have one girl and a large litter instead of multiple females, who can share the load and will even start lactating for pups when they aren't and have never been pregnant. If you're breeding for feeders, colony breeding is the way to go - one male, a large group of females, so every female can 'chip in' with the babies. If you're breeding for pets, females should be housed separately and introduced to the male only when you want to breed another litter - and let the female wean her last one naturally before you decide to breed again.
4. Completely depends. An animal who is bred - particularly if she's been back-to-backed - won't have as long a life as a female who is a member of a female-only group. Production tails off around one year of age; I've heard of people who've had mice live to three years old, but I've never seen one myself.
