I can't seem to find any reference material on their "NX" ferrule material. I found an AZB forum question from a guy who says they claim the ferrule is made from two different materials, which is pretty common with new "LD" shafts that have hit the market in the last few years. I also found a fairly high-rez photo of a replacement Mezz ferrule, which didn't specify if it was a factory made Mezz ferrule, or somebody else reproducing them. The material in the photo looked a lot like the Aegis material I use in my shop, though.
I haven't done a Mezz ferrule replacement yet, so keep in mind my advice is purely speculation based on working on other LD shafts which are marketed with similar features. I have replaced hundreds of ferrules, though, and some problems and symptoms seem pretty consistent regardless of brand.
As far as the tapering goes, it generally isn't something that necessarily means you have to replace the ferrule. A lot of LD ferrules are extremely thin-walled. The popular theory with LD shaft technology is that deflection is often attributed to the mass of the shaft, particularly within the tip end of the shaft. The general consensus is that if you reduce the mass in the end of the shaft near the tip, you lower "deflection". Some companies accomplish this by drilling or boring out the end of the shaft to make it hollow, then often filling in the void with a foam or some other type of "core" which weighs less than the wood that was previously there. Consequently, in the race to make the lightest and strongest shaft possible, some companies have even redesigned ferrules to make them very thin and light as well. Most ferrules used to be roughly 13mm in diameter, and were often installed on a 5/16" wood tenon. This meant that ferrule sidewall thickness was in the ballpark of .100" in most cases. Manufacturers could therefore use thermoset plastics like ABS, PVC, and other formulations to create cheap ferrules that would last a reasonable amount of time. With the advent of modern "LD" shaft technology and thinner profiles, ferrule diameter has shrunk from a common 13mm size to 12mm or less in some cases. Quite a few shafts are now standardly produced in the 11.75mm size now. A 12mm diameter ferrule installed on a 5/16" tenon now has a sidewall thickness of roughly .080". An 11.75mm ferrule on the same tenon now has a sidewall thickness of .075" at most. Threaded ferrules (like the Mezz ferrule) also now have the added problem of seeing this extremely thin sidewall scored with fracture-inducing internal threads which I feel like further compromise the strength of the ferrule. The end product is a ferrule which has the sidewall thickness which roughly equates to not much more than that of a credit card. In the case of Predator ferrules, they use a soft thermoset plastic material instead of a composite ferrule made from resin and cloth which would be quite a bit stronger. My best guess just by looking at some random pics on the web is that Mezz probably uses a composite ferrule material which is a bit stronger than the junk thermoset plastics, but I couldn't know that for sure until I get my hands on one.
If the tapering is essentially limited to the "cap" of the ferrule, then the odds of it weakening the strength of the ferrule are much lower. If the tapering extends back into the sidewall of the ferrule that surrounds the tenon, then the structural integrity of the ferrule is lower for sure. Will it cause ferrule failure? That is hard to say. Ferrules replacement is not super cheap, and I always recommend people to just play with it until you have a problem. I have seen some incredibly thin ferrules with deep scratches last for years and years without problems, and I have seen brand new ferrules crack the first night they were used. I'd just use it until you see a problem. One huge, significant factor in this whole situation is the mental effect of seeing the taper when you are aiming. If the tapering on the ferrule distracts you or bothers you, then I think that could easily reduce your ability to focus and play your best pool. In that case, you may find it to be a good investment to just have it replaced for peace of mind if nothing else.
As far as tip pads go, I don't see any correlation between using them and extending the life of ferrules or shafts or anything else. I think it is a mental thing, and a pad will often slightly change the "feel" of a particular tip. It is one of those issues of personal preference, and you should use a pad if you like the feel of the tip better with a pad under it. I can't say I have ever seen any measurable trend in equipment durability related to pads, though.