This is the quick refuge using the hammock and the poncho:
Be careful with creams/bug repellents as their scent can be felt from far away, so in tactical situations isn't recommended.
The ground pad as thatGirl suggest will help you keeping the temperature when sleeping on the floor, but is really bulky.
The use of the poncho and poncho liner are basically what you mention, although if is the only thing you have, you can roll yourself inside the poncho and that also will keep you warm, at least warmer than using nothing
The kind of refugee you use depends a lot of the climate, tactical considerations (such as visibility, noise, time to mount/dismount refugees, traces left etc) and what you're carrying in your BOB.
My suggestion is for you to go out and spend a few nights on the field in your OA, try to do it in different seasons also, the best way to learn about refugees is go out and try them, in my experience bugs were never an issue, but cold... That can fuck you up, specially if you can't have a fire.