VB Forms - Combo Boxes

I'm on Vantage 6.10.542 and putting a couple combo boxes on the Part
master VB form. Is it possible to restrict the choices of one combo
box based on the choice previously made in another?

Also, Is there any limit, practical or otherwise, to the number of
choices a combo box can have? Basically, my first combo box only has
maybe 10 choices but each choice could have 50 possible 'subchoices' in
combo box 2. Is it possible to 'lookup' the subchoices in another
table somewhere?

Is there a better way to do this than a VB form?