On the t.v. mount, go definitely on the brick, the grout will crumble and so will your t.v. The plugs, when you go to change them out, the white wire goes on the side with the silver screw on it, and the black goes on the gold screw side of it. You can put a green wire with a self tapping screw to the box, only if you have a metal box, which you should on a house that old. You can also just screw the plug onto the box without the wire, because, if the box is grounded, then your plug will be too. By code, the green wire needs to be put, however if you have no ground on the house, it will not make a difference. By code, if you don't have ground, you need to keep the 2 prongs, but people put 3 prongs all the time and it works fine, it's just not grounded. When you go to plug in the tester, you will only have one orange/yellow light in the middle on because you have no ground. Like Stocker said, you might need to run ground to each plug you change to a 3 prong, or know if something grounds out, it will stop at the metal box the plug is mounted to.
