You would need an EP to view the image. 2000mm focal length isn't as much as you might think. My 12.5" f/6 in almost that long and the longest F/L EP I own is 40mm. But there are EPs that I've seen as long as 70mm. I'll have to scach my head for a while over your second question. I'm not sure.

If you were to make an 8" with a 1500mm F/L, it wouldn't take too much to figure the mirror, even for a beginner. You would need a Foucault tester to check the figure. And a Ronchi grating is also a must. I have even made Ronchi gratings using clear plastic, a straight edge and a Sharpi marker. They work better than one would think. Turns out when you draw a line on plastic with a Sharpi, it dosn't make just one line, it makes a bunch of very fine lines.