A layout in my perspective is like you are laying out a tablecloth. You bring your leg up to about 90 degrees or higher and then sweep your head and shoulders back so that you are more or less a straight line (from your extended foot to your head). You then lean forward, bend your supporting leg and drop your head way back, you go into a kneeled/crouched position (sitting on the ground) and your head is the last thing to come up. Think of it as like a T, your extended foot to head is the top line, and your supporting leg is the vertical line.

NO idea on what the other two are!

Hope I helped!

A barrel roll is usually done out of a chasse and it appears as if you are rolling over a barrel, while your body is completely in the air. They are very hard to explain... ? Maybe look it up on youtube???

Rhomburses? Are you sure it isn't a "ronverse"? My spelling could be off on that... However, this is a motion with your arms, where your arm goes around your head- also known as a "shampoo" sometimes in dance team terms. They are often used in ballet.

Hope that helps!

Okay, barrel rolls are basically where you get a running start so you can flip yourself over in the air. Have you ever seen Newsies? I know it sounds dumb, but that will help you.

Renverses??? People call them different things. This is basically a fan kick where your standing leg comes off the ground as well and your arms mirror your "fanning" leg. Kind of like a waterfall over your head. Your standing leg can either tuck under your rear or can stay straight. This can be landed either up or in a lunge position. You might want to try checking this out on google videos, or youtube. I'm sure that actually seeing it would be much more helpful than me trying to describe it.