Well I don't think the controls are that weird. I just checked with Mega Man Zero 4 and the controls responds in the exact same way. And you know, when playing on the GBA, you can't push left and right at the same time. And yeah jumping is coming.

As for the collision detection, I'm not familiar with any common methods. But my method is related to the the map structure of the level. I've built a meta map system (16x16 tiles) and by checking whether or not a position in the map array equel to the current position of the player is 0, the player can move or not. Zero means that it's an empty area and you can walk through it. Easy stuff.