I don't see where the occasional bubble up the intake is going to cause any problems for your filter. I'm not sure about the snail not moving. I always thought they moved around the tank. As far as the plants go, you will have to find out exactly what a betta bulb is to determine how much light it needs.
www.plantgeek.net is a good place for help on that. Divide the gallon size of your tank by 15 (How many watts you have) to determine how many watts per gallon you have. I have a 10 gal. tank with 2 15 watt flourescent bulbs over it, so my lighting on that tank is 3 wpg. 1 wpg is low light, 2 wpg is medium light, and 3 wpg is high light. Plantgeek will tell you what type of light your plant needs to do well.