Will this work on a brick wall?

 Yes, but you will have to use the plastic wall anchors and lag bolts which should be supplied. You will, of course need to have a hammer drill fitted with the proper masonry bit to make the holes in the brick. Try to avoid the mortar joint if you can, especially for the top anchor bolts which bear the most pull out force. It's OK to use the mortar joints for the bottom bolts if you have to. Just try to hit the center of the bricks for the top bolts.

Does this mount have to tilt or it the tilt feature simply an option?

 I own 10 of these brackets. It's just an option to tilt. There's a big plastic screw that you tighten or losen in order for it to tilt.

Can this TV wall mount be installed using drywall screws? Can any of the monoprice TV mounts be installed to the drywall of a stud wall? This is for a 43 inch tv. Thanks.

I would say, technically, yes, as long as the heads are wide enough and the screw is long enough to go at least an inch and a half or two inches. However, I would opt for drilling into the stud with the appropriately sized drill bit and securing the mount to the wall using the included screws. This should be the safest and most secure method. If screws were not provided, get some lag screws of the diameter that easily fits through the mounting holes. Drywall screws are not made for this sort of application, so use them at your own risk.

Will this work with a 50" TV that requires a 200x200 VESA mount?

This is a good quality mount. I am currently using a 65" Q8 Samsung and it works great. I'm not sure but would guess the mount holes are flexible enough to meet your needs.