1. Depends on whether you neck size or full length resize. It also depends on how mild or hot your loads are. For a semi auto you must full length resize but for a bolt action you can do either.
2. You can reload some "military" brass. Lake City 5.56 brass is reloadable but you have to remove the primer crimp. Foreign military brass is usually going to be berdan primed, which is non reloadable. You also cannot reload steel cased ammo.