A triple to a compact double? There is no point beyond scoring style points at the local club rides. I know that this is said every single time that this comes up, but you should really reconsider making what is effectively a downgrade to your bike. It's an expensive change for no material benefit. If you want to upgrade to a nicer triple crank, that's great and sensible, although not really necessary. I would deal with your component issues on a case-by-case basis, and not bother with downgrading to a compact double. But if you MUST:

1. Yes, this would be the first step.

2. Don't bother. Your triple brifters will work fine, new ones are a big waste of money. Shimano brifters are very expensive, worse than Campy at equivalent group pricing points.

3. Definitely a waste of time and money. Upgrading your calipers will boost your "bling" but not your performance.

Save the money (which is a non-trivial amount) and put it toward that custom frame. A full-size triple is perfectly capable of letting you "kick it up a notch" if you so desire. If you want to feel faster, a tighter cassette (say, 11-23 or even 11-21) is a cheaper means to the same end.

EDIT: Regarding "kicking it up a notch," a full-sized triple will give you HIGHER top-end gears than a compact double. What you want to do is not only pointless, it is actually counter-productive to your stated goals.