I would highly recommend buying bees that are local to you, and I would especially not purchase bees that are from a significantly different climate from you. You want bees that have genetics that are adapted to your flows and your winters. I would also reserve packages or nucs early, as some places will run out of reservations by pickup day. It might also be a good idea to try and find a seller who is keeping bees the way you plan to keep them (i.e. try to buy treatment free bees if you want to be treatment free), because again, the closer the genetics are to your ideals, the better the bees will do in your care. I've never had "pure" strain bees (like Carniolans, Italians, etc.), but based on my experiences with local mutts, it's never been something I felt I needed or wanted.
A #3 package means a 3 lb. package. So instead of the bees being on frames, all the workers will just be in a mesh box with a caged queen and a can of syrup. I started with packages, and they are cheaper than a nuc, but you do have to kind of baby the hive for the first year depending on your flows, because they are starting completely from scratch.