First, what kind of plastic are you using? I print with PLA at 200C extruder temp on glass and do not hear my bed. I did treat my glass with a few coatings of hairspray for stickyness. Other plastics may do better on a heated bed search around the internet or youtube some and you can get some ideas. If you do end up heating your bed you may want to put a delay into your start GCODE syntax is G4 P# where the # is in milliseconds to allow the heat to transfer up through the glass properly
Second question My extruder is a little less than 1mm lower than the fan. This is so that the fan doesnt hit the print as it moves around. But I dont think this is an issue as the fan should be off for your first layer. There is a setting in cura for initial fan speed which on mine defaulted to 0.
Third you want to set your z axis stop not too low and not too high so that you dont run out of travel with your bed screws when you try to level them.
