I think the answers to your questions are: 1) no you can't use them in both places, even if it is the same day. They used to be $50/day, now they are $25/entry. This works out the same for you since you are looking at 2 entries. 2) I don't think you need to be skymiles member to buy the passes. If you do if should take more than a few minutes to sign up for skymiles.
Just a thought but since you are looking at $200 RT for access, you might think about spending a little more and buying a WC membership. That would also get you access to the CRC plus you would have it for your other travels as well as in HNL and perhaps at your point of origin.