Hi again Marilyn,
Believe it or not, we have a very similar problem with our 2004 3400RL that we just purchased used.
Our "black tank" hadn't been flushed properly and the previous owner had been using a formaldehyde (sp?) based odor chemical.
Here's a couple of pertinent points of interest: First, when you see water down the toliet hole (when stepping on the pedal and opening the trap door) you actually have filled up the 3" PVC pipe leading up to the toliet from the tank. This pipe plugs up easily and you MAY be able to get a long "wand" and (ugh) poke through the fecal material and paper product, but more likely, you can buy an inexpensive "snake" from ACE hardware or Wally's and poke through it. Note: The snake will NOT work to go all the way through to the drain because there's no pipe to direct it, and it just coils up in the tank. Ask me how I know that.
But the "tank" leak you have from the bottom may be the same problem we have. Take a look under your SINK in the bedroom and check out the water coupling at the vacuum breaker/vent that's located under the sink. You must have your tank flusher hooked up and the water turned on to check this, but if you have the same problem, the water drips down the plastic plumbing and finds it's way down to the ground. It's clean water by the way, so if yours is.....uh...black, then it's probably something else.
hth,
Richard