Hello! I see you are fairly new to the forum, so welcome!
1. Washing it with warm water and either bleach (very very tiny amount) or vinegar works well. Wipe it with the water/bleach or water/vinegar solution very well, lots of elbow grease! Be gentle around the silicone though. Once you're done that, rinse it really really well. Then let it air dry.
2. I'm not really sure about compatibility. I've heard AFDs are good tankmates in a 10 gallon. Neon tetras are also good, but your tank needs to be cycled for them, and they need to be in groups of, I believe, 6 or more. Snails are cute, but they have a high bioload. Shrimps are very good, they help clean the bottom, and have little bioload. If you don't want to do a lot of cleaning, I think shrimp would be the best.
3. The more plants the better! They help with the cycle, because they absorb all the bad stuff. :) I believe anubias can't be buried, it needs to be tethered to something. You can use fishing wire to tie it to a rock, or decor. Since you like drift wood you could tie it to the wood, same with the moss. It will grow all over your wood if you tie the java moss to it. I'm not sure about the stem plants though.
Pewpewpew made a very helpful plant guide here: http://www.bettafish.com/showthread.php?t=67565
maybe take a look at that.
4.An adjustable heater is the best. The pre-set ones usually never go to their preset temp. I'm not sure on a very good brand, but I think marina is a good brand to use. Don't forget a thermometer!
Don't forget to post pics when its all set up!