Regarding freezing cake made from cake mix, I did, and do, this all the time.
I used to do cake decorating as a side line for extra money. I even took the Wilton Cake Decorating lessons. They recommend freezing your cake, and frosting (icing) it frozen. Less crumbs and easier to frost.
By all means, freeze your cake mix cakes. This also gives you the option of having a cake to serve anytime you want one. Bake ahead and freeze.
I always use Duncan Hines cake mixes. I find they are best. When I was doing cake decorating for extra cash, no one knew that the cakes had ever been frozen. Actually, everyone thought the cakes were made from scratch and fresh baked!
Happy Baking!!
Lee