Yes, there are standard bunk bed rooms.
Yes, they have a trundle, so the bunk bed rooms sleep 5.
BUT, they will also provide sleeping bags on request, in the event that a child WANTS to sleep on the floor.
The request for a bunk bed room is ONLY a request though, although they are MUCH better at honoring these requests at DLR than at WDW. They acutally assign rooms at DLR further ahead of time, I believe. At one time, I was reserving a room at GCH, and I inquired about the availability of a bunk bed standard room and was told, "there are no more bunk bed rooms available for those dates", even though it was a few months out...so I do think they "sort of" reserve them, even though it's not a bookable category. I had to change the dates and upgrade to get the bunk bed, and it all worked out.
I have been in a bunk bed room in Theme Park (once) and Concierge (standard view--twice) now. So, three times total.