Bill, I have dealt with bladder sludge and stones. I will tell you some of the things I do from home. The way I think about it is the more fluids you have going through your bun, the better chance you have of the body expelling the sludge itself. There are several different things you can try to get more water in your bun. What works best for me is soaking my bunny's greens for atleast an hour before giving them. That way they can absorb as much water as possible. When I give the greens, I give them at a time I know the bunny is most likely to eat them right away. If I give her greens when she is having free roam time she isn't going to eat them right away. So I give them to her when she is caged in her room. I don't shake the greens or anything I take them to her dripping with water. I have also tried flavoring her water with juices. I tried making my own juice using her favorite green and blending it. Right now my vet is getting me the banana flavored stuff they use to compound meds and I am going to try flavoring her water with that since my other flavoring attempts didn't work. She has lots of options in her room to drink from different things. She has 2 water bottles, 3 water bowls and a cat water fountain. I also make sure anywhere she goes in the house for free roam time has a water bowl.
Most sludge and stones are made from calcium so I try to feed low calcium veggies and hay. Here are some links that give calcium content.
http://www.carrotcafe.com/f/calevel.html
http://www.carrotcafe.com/f/caforage.html
Also giving them lots of time to run and jump gets the sludge moving around in the bladder so when they do go to the bathroom there is a better chance more sludge is expelled.
I have done sub q fluids at home but have never expelled the bladder myself. My vet will sometimes try to expell the bladder to get a urine sample to check the calcium content of the urine. I usually get x-rays to tell how much calcium is in the bladder. My bun goes once a month for a check.
When Chase was in pain she would sit in her litter box and try to go but northing or very little would come out. She would keep moving and trying to go. She would also go outside her litter box which is unsual. I also could tell by the way she would lay. I wouldn't say she pushed her stomach to the floor but I could tell that she was in pain. She would love to lay on cool surfaces. She hides the pain well. One day she would seem fine and the next I could tell something was really wrong. That is one of the reasons I go for monthly checks because it is hard to tell when they try to hide the pain. With the symptoms I described above, that would be when I would take my bun to the ER vet. So they could administer fluids and pain meds. Since I have been through this so many times my vet has now given me pain meds to keep on hand at home so if I see she is in pain over the weekend I can give the meds to hold her over until Monday.
I tried to answer all your questions, if there is something I am missing or you would like more information just post here and I would be happy to answer anything.
I also wanted to say I would have done the same thing you did and bring my bun home when you did. They really do better at home. But I do think frequent checks are need atleast during the beginning as you can't know how fast this will come back. My bun had 2 bladder stones removed in 3 months. After the 2 stone was removed and she went back in to have stitches removed, 10 days she already had sludge. You just can't know how soon it may come back, if it even will without x-rays.