You don't need anything else attached to the board other than power, thermistor, extruder heater cartridge and some way to control the nozzle temperature (LCD or USB with pronterface [or other software]). You are not using any motors so stepper driver heat sinks are not needed.

I put the nozzle in a small metal vise to hold while it was heating, but that is just because I had one handy. Glass will certainly not melt and shouldn't scratch or anything. My only worry there would be too fast local heating/cooling.

I actually did do mine out of sequence, but only because I finished the build while waiting for my power supply to arrive.