45 Auto is the official caliber name.
45 ACP is the Colt trademarked name.
Break in length is kind of your choice. Break in is wearing of small burrs or cutting marks to smooth or to the point there is enough bearing surface to support th load. The number of rounds required depends on the quality of manufacture.
There are tons of 1911 mags. Before you start spending $50 each for magic mags, ask yourself why you need them. A nice ~$10-15 Springfield mag which holds 7rds, wadcutter lips and the dimple is a pretty good mag which matches the modern 1911 design. If you are not feeding well with this kind of mags, mag replacement is wishful thinking. A gunsmith can help with the issue. Checkmate makes a few versions of this style mag and are good also.
Wilson mags work, but are more spring sensitive.....probably due to lack of a speedbump on the follower.