1. Technically, everything on a board could be removed, sorted and sold separately, but just starting out that's probably not what you want to do.
There are certain things you definitely want to remove like batteries. Lostinlodos did a write-up on that
here. (After writing this I've realized I should say, Do Not Remove anything you're not able to safely, as I'm not sure that's clearly stated on that thread)
I did a breakdown recently for another user about the value of the boards
here. If you want to read through that I think it could help.
2. Connector ends are things like the actual plug that you connect to different ports on your computer. So HDMI, VGA, USB plugs. The reason Boardsort can buy these is because the pins are gold plated. The gold plated pins have a separate category (currently $5/lb) versus connector ends ($1/lb) due to the excess plastic and metal weight.