I would suggest trying to find a more steady heater, preferably adjustable. I have an Aqueon 100 watt in my 10 gallon, and it works great. Heats exactly to what it's set to and it has a life time warranty! :) Definitely does its job.
I have almost the same stocking as you, put plus another snail and minus the ADF. :) I use the filter that comes with it. I'm going to assume you and I have the same tank kit, so we have the same filter. What I did to make it not so mean to the fish is I baffled it more. I got a Fluval Edge filter intake sponge. It's a cylindrical sponge that slips right over the intake (where it's sucking the water in) and it slows down the flow a bit. To redirect the flow from shoving them around, I cut the middle of a water bottle and used a rubber band to hold it in place to the filter lid. There's a tutorial on here somewhere about how to make the water bottle baffle. :) It slowed the flow down A LOT and now he can make a bubble nest wherever he wants without the current breaking it.
If you have a filter, the tank can cycle, which makes cleaning it WAYYYY easier. Until my tank is finished cycling, I do two 50% water changes a week, using a gravel vacuum to clean the gravel and suck out the water. I swish the sponge and filter cartridge in the old tank water and put them back, then start filling the tank up with clean water. Sometimes I rearrange everything, just so they don't get bored. I don't scrub the sides of the tank or any of the decorations. All I do is clean the gravel and take out the water.