There is very low variance in surface flatness. So measuring 5x5 will give you very close to reality value of the spot between measuring points. Not like with stock build surface, where between the grid you can have huge crater or a bump from a hot pulled print. Rigidity helps too. Thicker garolite is like glass, but not brittle.
Check out this video about it.
That is correct, but you can use any variance of probe mods available here. Non of them are actually measuring the surface tho. This is the main reason I went with mechanical klicky probe. Check out Fifx mod and proximity sensor mod for alternatives.
Yes, no intermediate adhesives, just wipe with alcohol and PLA, PETG, ASA/ABS - all stick really good to it.
Once you let it cool down a bit, it pops right off - sometimes I get that satisfying click of separated part, but most of the time - it’s 99.9% separated just due to difference in thermal expansion/contraction.