re: I'm going to be building a farmhouse table soon. Any tips?

A good wood glue like Titebond will suffice for gluing the top. It will actually be stronger than the wood once it's cured. If you don't have a jointer, you can use a hand plane to square the edges and fit the boards together. It takes time to do it right but it can be done.

Yes, only glue the joint in the center of the breadboard end. You should still put a dowel through the mortise and tenons of the other joints but leave a small slot in the tenon to allow the dowel to move side to side.