Crayfish questions (Food/Housing)

So, I've been debating for years about getting dwarf orange crayfish, and now am taking the plunge. I am buying from Elite Inverts, because I've heard good things about them.

Anyways, they have a very good selection of foods to choose from on there, as well as supplements and after looking around, I'm going with Shirakura Ebi Dama Special Ultra and Shirakura Chi Ebi. Judging by the price alone, I am thinking they are a good choice. Am I right? I also have about half a bag of Tetra Veggie Algae Wafers left over from the purple apple snails I had, but have since all died off. I chose it because it had extra calcium in it. Would it be too much calcium for the crayfish if I fed both the veggie wafers and the Ebi Dama Special Ultra to them?

I am getting the Ebi Dama Special Ultra because Elite Inverts suggested getting a highly nutritious food for an unestablished tank. I am also getting the Chi Ebi because Elite Inverts said it had micro-organisms that helped to break down food films and such, and would be good starter feed for baby crayfish, if the two I get reproduce. Though, I don't know the chances of getting both a male and a female together. Maybe getting a gravid female would be better odds? Maybe I am being a little to presumptuous here.

Anyways....

I've previously torn down my 10 gallon tank completely, the tank I plan on setting back up for the crayfish. I've done the research on how many to stock, which is 2, but I haven't bought them yet. I am waiting to get the tank up and cycled again. Would it be better to wait til the tank is fully cycled until I get the crayfish, or would it work to put them in while the tank is cycling? Would they be susceptible to ammonia spikes like actual fish? I should also add that my water is naturally a pH of 7.8. Is that high enough for crayfish?

I know some of these questions are rather silly or common sense to more experienced aquarists, so I apologize for that.