http://www.mainelegislature.org/legi...2sec11209.html Make sure you consider ventilation if you're going to shoot in a basement. There is a very real risk of lead poisoning from inhaling the fumes in a confined space.
As to your second question. If you do not have a Concealed Handgun Permit, then the magazine cannot be inserted or attached to the firearm. Having the mag loaded is fine. I used to put the mag next to the gun on the passenger seat. It doesn't even have to be in the glove box. You do not need to unload the rounds from the magazine.