I would go with the Ryonet emulsion vs the Ecotex. I would also get the UV blacklight vs the 500w, your times will be much quicker. I use a 20w blacklight with my exposure system. Also get the Green Galaxy ink instead of Speedball. You will also need an emulsion remover.

Get a scoop coater that is 2" smaller than the inside dimension of your screen, that way you have an inch on either side. You will be coating going the long way on your screen, so for a 16x20 frame you would get an 11" coater. I use a 15" coater for 20x24" screens.

A 16x20 frame is going to be 13x17 inside dimensions. You need a few inches of room at each end for the ink and starting/finishing your print strokes. That means a design of 10x11" or so. You also want to leave at least an inch or more on each side of the design. I would encourage you to get a 20x24 frame instead, and buy a few frames instead of just one.

A 16" squeegee will not fit in a 16x20 frame going lengthwise. frames are measured externally. Most of my designs are a max of 11 x 15", and that's using a 20x24" frame and 13x19" transparency.

How are you going to cure the ink? A heat gun and laser thermometer are a cheap way.

Are you going to print your own transparencies?