I've exported a model from Max, and placed the origin at the feet of the model. When i run my level my model always runs along the level a few quants above the floor. If i move the origin to the knees it runs along the floor but then it goes under blocks that are just a little bit off the ground.
its always best to have the models origin at about hip height in the centre of the model this makes stair climbing easyer. as for the other problem try useing c_move.. it realy works!:)