I would get the basic kit, then do some research on the many threads here (or simply call TNVC) and decide which mount you would prefer to get.
I wouldn't worry about the "weapons mount kit," and the Ops-Core helmet you listed already comes with a molded in shroud, negating the need to get the accessories that come with the "full kit."
Mounts can be expensive, and with all the myriad options out there, it can get a little confusing and overwhelming--but a good mount can really "brighten your night," so to speak. If you get a dovetail-interface mount, you will need a new device interface to replace the J-Arm in the kit as well.
The other big piece you're missing there, is, as others have mentioned, some sort of IR aiming laser/light, which again, there are a variety of threads on the pros and cons of various different models, and you can go in a number of different directions with them.
NOD, helmet, mount system, and IR aiming solution are the "big ticket" items.
Other things you can try out and see what your needs are and pick things up to address them.
This is all, of course, assuming you already have a capable weapon with a visible light, and preferably an NV compatible optic as well.
Beyond that, read a lot (it may take some practice to filter out the wheat from the chaff, but good information is there), and ask whatever questions you might have--the folks here generally tend to be a little more tolerant of the same questions being asked over and over again (this particular thread/question is more or less a bi-weekly occurrence here--but it means you'll have lots of archived material to read and ponder over).
There is a certain amount of inevitable repetition on this forum, as new products are, frankly, not that common (compared to the rest of the "AR industry"), and ultimately the number of different devices/manufactures/products/vendors is pretty small, again, at least when compared to the rest of the market.
For example, there are only really a couple "duty grade" IR LAMs available out there available from a finite number of vendors, compared to everyone and their mother making an AR barrel, BCG, rail, stock, and trigger out there for people to argue endlessly about.
~Augee