The name comes from Masc:
I would say even worse... the moiree is so extreme, that you can see it in liveview already.
Horizontally, I'm pretty sure the "properties" are actually the CMOS registers. I'd start by comparing CMOS configuration before pressing MENU to refresh LiveView, and after.
Caveat: adtg_gui won't work at the same time with crop_rec, so... it's going to require a bit of guesswork. Maybe print debug messages from crop_rec's cmos_hook and figure it out from there.
Digital zoom in 720p... not sure what the question is. Frame rate limits are given by resolution and pixel binning mode. So far, I wasn't able to alter them by starting from some other video mode.
720p normally works by skipping more lines (5x3 vs 3x3); that lets you reduce vertical resolution and increase the frame rate. With 1:1 crop, you are no longer able to do that (unless you use 3x1 with line skipping, which... let's just say it's not the best idea).
Theoretical readout speed on EOS M (and also 700D, 650D, 100D, M2 etc) is 32 MHz x 4 channels. In theory, it should be fast enough for 1080p48. In practice, maybe not. The 700D can do 1736x1160 (3x3) at about 43 FPS IIRC (didn't test it myself). That would be timer A = 520, B = 1431. For 48 fps, you would require B = 1282. If you trim 150 pixels vertically, that should do the trick.
See
700D.png and
700D-crop.png (from
here). Most of the overheads are from the hardware (some of them *might* be tweakable via ADTG registers, e.g. see
this picture from 1100D). There is also a software overhead of about 2.5 ms
on 5D3; exact value may be different on other models.
The 1100D is an interesting beast - it uses
CH4-6483, i.e. the same 32 MHz x 4 channels interface as the early DIGIC 5 APS-C models (that's right, 1100D isn't your average DIGIC 4 cam), yet it has its sensor severely throttled in video mode, likely from ADTG configuration. Comparing ADTG/CMOS registers between 1100D and EOS M / 700D / 650D is likely to reveal the key to adjusting these timing "overheads" (or whatever they are).