There is a jig for drilling the holes for deadbolts and other locks. It positions the holes for the lock in the right position to each other and helps you line things up with the door frame. Since you have a metal door you are going to have to make sure to use carbide or diamond tipped hole saws. By the time you buy the jig and the hole saws (you will never use again?) you will probably find it cheaper to just call a locksmith.
A locksmith can also rekey your existing lock cylinder possibly to the same as the deadbolt so you don't have to carry two keys. You can save yourself a bit of labor/money pulling the cylinder yourself and taking it too the locksmith.
Yes you should reset your alarm code.
As far as damaging the magnetic sensor? You should not have to worry about damaging it by drilling for the deadbolt. If you goof you are going to mess up a nice metal door though. Make sure you are up to this as a DIY project.
A locksmith can also rekey your existing lock cylinder possibly to the same as the deadbolt so you don't have to carry two keys. You can save yourself a bit of labor/money pulling the cylinder yourself and taking it too the locksmith.
Yes you should reset your alarm code.
As far as damaging the magnetic sensor? You should not have to worry about damaging it by drilling for the deadbolt. If you goof you are going to mess up a nice metal door though. Make sure you are up to this as a DIY project.