there are animation blending functions... you will have to use them, it is not pleasant. You will have to write an animation manager to handle this stuff...

The only way to do this is to use bones (.fbx import). This is a pain in the neck as it will fail, the most common reason being you have more than 3 skin weights per vertex... keep it at 3 or under (2 is better performance).

Out of maya the .fbx import will fail if the material is not a lambert... etc. Stuff like that really throws it.

You cannot touch the bones in med if you have more than 1 skinweight per vertex, it will not like it.