I did put some sponge material at the bottom intake as well--not too much just a little so the intake wouldn't be too strong. Lord Granthum doesn't seem to go near it anyway. They seem to like to hang out by the filter intake more when it's at the top.
The rubber band holds some sponges that I have to slow the outflow.
Not very pretty but you can't really see it when the lid is on.
As far as priming, you should have the back chamber all filled up with water before you turn on the filter. Other than that, you should be fine.
I keep the heater at 80. It doesn't have a thermostat, but there is a dial to adjust up or down, so I have to play eith it a bit and monitor with a thermometer, but it seems to hold the temp pretty well.