If an object is moving about some circular/ovaloid path, and the magnitude of its velocity is changing, will the objects acceleration vector still be perpendicular to the velocity vector? I'm tending to think that it won't since, I think, that some component of the acceleration vector would have to be in the same (or opposite) direction to one of the components of the veloctiy vector to institute a change in the magnitude of the velocity.
You are correct -- *if* the magnitude of velocity is changing then there must be a non-zero projection of the acceleration along the direction of the instantaneous velocity, and hence v(vector) and a(vector) cannot be perpendicular.