1) The best thing you can do for this is to learn a system of divination and practice it regularly, so you get good at it. It's very difficult to work out a set of conscious questions that will cover the territory; on the other hand, it's fairly easy to do a divination asking, "Is this ritual intention something I should do?" and let the answer guide you.

2) The differences between the two systems are extensive, but they cover much the same ground in their different ways. Both require about the same investment of time and will yield comparable results. How should you decide between them? Read the books in question, imagine yourself doing the practices, and see which one feels right. It really does depend on the personal element, and on individual nonrational factors.