1) Should you grease the steerer tube or leave it dry?

2) Is teflon grease adequate for the headset bearings or should you really get proper bearing grease?

1) Greasing it is definitely a good idea, but not 100% necessary - however, do it, it'll run more smoothly.
2) I'm not too sure, but I think it should be fine.

1) a light application of grease around the bearing contact areas is sufficient.

2) yes