I think plenty of folks do transition straight from SP to an LD - but i think my own problem is that I'm too far away from the proper REM cycles in terms of timing. I think that's why they suggest to wake up from sleep about 4-6 hours after going to bed, stay up for a bit, and THEN try to WILD. Your brain is in-between REMs at that point, which makes it a bit easier (maybe a lot!).
I think when they say 'hypnogogic images' they are talking about the lights/patterns/swirls/colors you see underneath your eyelids when you close your eyes.
I don't know about the sweating, though!
I wish I knew how, but I can't seem to figure out how to get past the SP part of things to drop straight in to an LD . . . . only had a few LDs ever that I can remember, and just started trying to recently. . . about 2 months. Let me know if you get something down that works! I'll do the same!