Yes, you have correct links to both products.
One of the biggest issues with a dry suit, as opposed to a wetsuit, is that damage to a dry suit can render the thing unusable. If you are diving in cold water and tear a neck seal, you are done for the day . . . or, if you have to send the suit off to have the neck seal changed, for days to weeks. With the Necktite, as long as you have brought a spare seal with you, you are back in business in about ten minutes. Having ripped a neck seal on a trip to Southern California, and done the dive duct-taped together (and rather unpleasantly wet), I appreciate this. The bigger the trip, and the more remote the destination, the more dive gear seems to want to fail on you . . .
The Viking rings install on the seals of the suit. They can be put on or taken off in about three minutes, with no tools. Therefore, if you decide to use wet gloves, you can easily do it, without any rings on the suit to get in the way. I don't know anyone who switches back and forth from dive to dive, but I do know people who dive dry gloves in the wintertime and wet in the summer. And for me, it's nice to be able to take the ring system off altogether when I go cave diving (where I wear no gloves at all).
Installing a p-valve on the Fusion is not difficult -- I've now done three of them. The big challenge is making the hole in the skin look neat and professional, and I haven't quite conquered that one! The new Light Monkey valve has the same stop screw arrangement as the Halcyon valve, so you really have to work to lose the cap on the valve. I really can't imagine diving without a p-valve any more -- even if you had a relief zipper, the waddle up the shore with a full bladder is an awfully uncomfortable thing.