Like this: (legs->) ./_0 (<-head)
I have been awoken like this twice from an LD and had a Very vivid dream with this position. The problem is that it might be harder to sleep like this than just sleeping on your back.
I think the reason that gives you more awareness is because the circulation on the legs is delayed by being in a upright position thus making you conciouss of your legs before drifting off.
Yes! I’ve tried that. It’s much more comfortable than sleeping with your arm up and hoping it’ll wake you a bit when you get sleepy enough to let it fall.
Personally, a little too comfortable 
I just have normal dreams in that position.
But for some reason, I was able to initiate sleep paralysis from sleeping upside down (that is, lying on the bed with both my feet propped up on the pillow where my head would usually be, and nothing propping up my head because my head is where my feet usually are.)
The Tibetan Buddhist also have different postures for sleeping to help induce LDing. Tibetan Buddhist Surya Das has a audio study guide called Tibetan Dream Yoga. He gives examples of different sleep postures.
thanks very much for the info.