I've kited yallingup a few times.
I (and some of the locals) launched from down the beach through the shore break (known as rabbits). The winds in there are slightly flukey and the shore break is normally pounding, so I'd only recommend it if your confident (or conditions are favourable). I'm positive you must be able to launch across the lagoon on a high tide, but I've never done it.
Out the back the waves are big and fast, but actually have a fairly flat shoulder (on the main left) making it fairly safe. My first few waves here were a nice wake up call after riding Cott. A board that your confident to ride at speed as you race down the face will help.
As for margrets, I've never done it, I hear you don't want to get in the local surfers' way because they're protective of 'their' break. Meh. Go for waves when they're too busy paddling