Don't worry about the double posting, Fan. A new day for a new post.
As for your questions:
1. Yes, I believe that's all that we know about Nick's powers. He is some how able to time travel, but not sure how. I believe he is feeding from Artemis. He does share sight with Stryker, which he tries to avoid when it comes to the DHs.
2. I think Cael is the one one who died. Cael was killed in Rayvn's book (The Darkside of the Moon), but then was brought back as something else. I believe Amaranda fed him her blood thinking as a last resort, which changed something in him. We don't know if he turns 100% Daimon or what. The last thing I remember is that the couple was on the run and maye Ash knew about it.