I'll try
1) I've found 30s to be fairly universal although the bright targets like Orion or Ol' Horsey 10-15s.
2) All calibration is taken at the same gain, offset and temperature as your lights. Bias - short as possible but 0.001s should work. Flats - 1-3s
3) Calibration. I think the flats do it specifically.
4) Not a lot if at all, DSLR is osc technically(ish)
I use -10C, the lower the better noise reduction BUT it can cause dew on the sensor glass. I tried at -30 and -25 and had troubles. After a bit of research it seems below -10 the noise reduction returns are diminishing.
Flats can be taken with a white tshirt and pointed at the dawn sky: "sky flats". Or a tablet with a white screen, any browser/pic viewer that works for you will do. Or a led tracing panel, you will need a few white a4's to mute the brightness enough probably.
Welcome to the cool club
