Yes, you can charge through the discharge leads with that charger. However, you should get a balancer and make sure the pack stays balanced. I find mine are out every 3rd flight or so. It depends on how low you let the battery get.

Main gear requires a little convincing. I had to brace the heli and gear and use a small hammer to tap it onto the main shaft. Try sanding a little, it might make it fit better. I'm sure you can see there is a "D" shaped hole, so it only goes in one way.