If you're going to do this, do it right. Don't cheapen your efforts by mixing real and fake plants. Go real if you can.
If you go the bamboo route be aware that the fastest growing plant is a species of bamboo (at something close to 46" growth in 24 hrs.) But real bamboo can be incorporated into your display by splitting the bamboo you can make great water ways. Whole bamboo that's been hollowed out can make an outlet for a water fall or pieces of bamboo can be used to allow amphibious creatures another path out of the water.
There are many varieties of fresh water shrimp that would get along peacefully with a betta. There's also some filter feeding shrimp and crayfish that're completely harmless. Be careful of the more agressive inverts that won't hesitate to snatch up a slow moving fishy. Clams, muscles, and snails would be good choices as well but the first two require more maintenance and a careful watch because a dead one can foul a tank in no time. Mangrove plants could be another option... Lillies could be beautiful. Lots of possibilities. I can't wait to see some of the initial work. Good luck!