I agree, 5-6 corys would probably be ideal. They are schooling fish and will be much more playful and energetic if you get around a half dozen of them, or at least 4 as an absolute minimum. They are cute little buggers, and before you realize it you might find yourself considering them to be the favorite fish in your entire tank! (If that happens, don't say you weren't warned. hehe.)
A few of the smaller loaches (Yo-Yo loaches, etc.) would also accomplish the same thing, but my experience with them is they can be active to the point of being hyper and when they are not in a really large tank, that can spook some of your other fish if you have anything that is the more peaceful, slow-moving sort (like a betta). Plus, if you should ever decide you WANT smaller sized snails in your tank (e.g. MTS if you have a sand substrate), then you don't want loaches as even one loach will hunt down and kill every snail in there in short order.
As for getting more vegetation...IMO, the more the better. Fish tend to feel more comfortable if they feel they have a place to hide if needed. So you might want to buy enough plants that you can take at least one portion of the tank and make it pretty thickly "planted." Heck you might even consider making the jump to real plants; the nice thing about them is that they GROW, so you can start out with only a few and if your lighting conditions are good, they will gradually (or sometimes rather swifty) get significantly larger. Obviously there are a whole host of things you need to consider (how strong is your lighting, do you want to deal with fertilizing, CO2, etc.), but long-term it might be cheaper than buying up a whole ton of plastic plants for a 35g. Just a thought.