1. No one has an answer, so I will assume that Trump has no actual idea either, and it changes every week or so.
2. I do not see the logic in just giving him money, and hope that he settles on the version that will be the least wasteful.
What barrier, and where it is to be located, and how long it will be. I believe he is talking about adding 100 miles of fence, not a single one of you Trumpsters will confirm that. And if Trump is proposing to add 100 miles of fence to the existing fence, then he should come out and say exactly that. He hasn't.