I helped a classroom teacher (friend) get set up and buy one. I honestly do not know what kind it is but it does eat mice :) Personally I would not recommend keeping the snake out in a cold garage, they need a warming light even when indoors (need to be kept at 77-87 degrees in cage, impossible for a cold garage and a heating light). This would be an indoor pet. You can get smaller ones, but I do not remember what they eat since my friend decided to go with a medium size one that eats mice. If I remember correctly ALL of the snakes ate frozen mice/rats once a week or so.
Just to start out I believe my friend spent easily $600 to get everything that was needed... then there is the additional cost of food and cleaning items that need to be picked up here and there.
The BEST thing you can do is go to the pet store, by yourself and ask them the above questions. Price everything out there, tank, everything to go inside of it, how often to clean, what needs to be replaced at every cleaning, what the smaller snake costs, what the price of their food is.
You are husband are going to need to help with the cleaning, so handling the snake, the food (snakes are prey eaters, so it is healthest to give them prey/frozen animal for them once in awhile), snakes live 20 plus years so it is a very long term pet (you will be caring for it when she is off to college), snakes are great at escaping so you must check the cage everyday & after ever time it is open to make sure the lid is in good shape and secured tightly... if that is too much I would say no to your daughter and look at a hermit crab, turtle (but those are tricky too).
Garter & rat snakes usually only reach 3 ft but can get up to 4/5 feet... but they may bite, smelly and will leave a smell on your hands when handled.
King Snake usually reachs 4-5 feet... has a good temper and easy to handle.
Corn & Milk Snakes usually reach about 4-6 feet... but are nervous and harder to handle.