GSI makes first rate aluminum and anodized aluminum DOs. I've used the regular aluminum ones before and was pleased with their performance, taking into consideration that aluminum will not cook at all like cast iron does. I prefer cast iron, but I would sure consider aluminum DOs were it my back that had to hod them up the hill.

I always cook the wax off over the grill or a fire. Really though, you don't need to worry about removing it all. The first seasoning will take care of that well enough, just make sure you do it outside. Also, best to either store them with the wax on or else season them up. Storing them in the raw will likely lead to unnecessary rusting. The crack was most likely there before you got it, and was concealed by the wax etc at the time of purchase. When in doubt, suspend it and hit it like a bell, if it has a crack it will sound like a cracked bell. If not, it will sound like it should. Do it with a known good one and you will know what to listen for from now on.

Dump cakes are pretty much a standard for me, though it's been a while since I made one. Not quite a cobbler, more than an upside down cake, they are fair tucker as my Brissy mates would say.