LSAC keeps them all on record for you. Some lawschools want an extra copy sent to them as well, but most want it straight from your LSDAS file. If you don't have one yet, contact LSAC to create one. They can store 4 LOR's for you and let you pick which ones to send to which school.
As for LOR's you "can" use a boss, but I'd only do it if in a legal career field or if you didnt have any better options. Teachers are always a good choice, especially in any prelaw courses if you took any(although prelaw dosnt help prep for lawschool in reality, it does look good for LOR's)
Also, you need an offical sheet from LSAC or they won't accept it, so get that. Then have the recommender send their letter to you and you send it in to LSAC. You could have them send it directly, but that way you can see what they wrote in case you want them to make changes to it first.