+1 for the rivermouth being an average place to kite. great place for other activities though, and horrocks, gregory, Lucky Bay all worth a visit.
maybe continue on to Shark Bay/Denham for a few days if beginner kiting is your trip focus - seems way more suitable.
re: the dredging, it is annual maintenance dredging that's been done since the boom fishing years. my mail is that this year the channel is pretty good and it might not happen.
here's another aerial photo - as you can see from comparing to the other, heaps of change with the sand bars year to year.
cheers