They absolutely accept letters of interest/intent. I sent a letter of interest in around Februaryish. When I was waitlisted in March, I decided that of the remaining schools I had been accepted to/waiting on, Brody was my for-sure #1 and I sent in a letter of intent in early April. I got accepted off the waitlist less than a week after they received my letter of intent.
As for status.. I know how it feels but they won't be able to tell you much of anything about your status. You may be told that your app either 'hasn't been reviewed' or 'has been reviewed once' but only a small percentage of accepted apps are accepted on the committees first look at it.. so that really only makes you worry for no reason. And as far as the wait list goes, they do not release any information about your 'position' on the wait list.. only that the wait list is roughly the size or slightly smaller than the class.. ~70-75 people typically.
Hope this helps,