for 1, you just need to add end gcode - which all the current slicers support. Just a simple "G90" to go to relative mode, followed by "G1 Z50 F1000" (you can change the 1000 to whatever speed you want) and then "G91" to go back to absolute mode.
for 2 - there is no easy way. You need to stop the print, manually move the head up so that it does not melt the printed object. At this point you can manually turn off the heaters, but not the printer or PC. The next day, get everything back up to temperature, make sure filament is flowing, Do a G92 to set your E axis back to what it was, manually lower the print head, and then resume the print. There's a LOT to consider if you want to do something like this. If you try to split your G Code into two files, you need to take care when you resume, that when you move back to the starting position that you do not collide with the object on the bed.
It is probably best just to let the printer go unattended. I've done it MANY times. Make sure the print gets through the first 2 layers OK, then just let it go
