Dialectic: logical argument, reasoning, rationalization. So, the "dialectics of capitalism" are the arguments and reasoning that capitalists use to justify and legitimize capitalism.

"As good a place as any" is a phrase that people use when they need to do something immediately, and they have no option but to do it where they are right now. It basically means "this place is not ideal, but I have no other options so I will have to make it work". For example, if someone is in the woods and they cut their leg and it's bleeding everywhere, and they have to put a bandage on it to avoid losing too much blood, on the ground is "as good a place as any" because there is no way for them to get to a hospital or a doctor's office in time. This phrase can also be used in less dire situations, for example when talking about where to put a package on a messy kitchen table. When no one place is obviously better than the others, anywhere on the table is as good a place as any.

"Did you have your breakfast" is correct. You can also say "have you had your breakfast?" and it means the same thing. In this context, "did" and "have" are helping verbs that make the sentence past-tense, and the verb that tells what is happening ("have") is in present tense.

Nonuplets; also I would say "nine children born at the same time".