As far as Gunner and the rabbit. I don't let Dandy alone when she is out of her cage. I am at the computer when she is running around. Gunner is VERY docile he lets my dwarf hamsters run all over him and he plays with my cat all the time. He's never snapped at anything or anyone. But I am always careful anyhow.
As far as the litter goes. That's when I first got the rabbit and I have switched to aspen in the cage and there is a litter box. That is temporary I plan on getting an xpen with in the next week or so. I then will buy a regular size cat litter box and take the rest of the bedding out.
She has toys, twigs and a house in her cage. The first pictures I took I literally JUST got her and her cage was empty.