Yes, FGU is 64 bit.
There is no FGU product to get
yet. For those on the KS who paid extra they are expected to get an alpha release, with bugs and all, next week (or so). For those who pledged on the KS, they will get access to the beta build sometime before December, but we don't know when.
And, FGU itself is expected to be production released in December, but exact date, details, cost for not KS people, is still unknown
You can purchase current FG (i.e. FGC) now via the store link above, you will not be able to purchase FGU until it is released, circa December this year.
You don't have to buy anything in FG other than the license. You can buy the FG versions if you find them useful (most of us do) or you can manually create your own reference books or just enter what you need when you need it. They FG versions are not full price, they are roughly half price but their are no discounts for owning the hardcover versions. See this post for more info on what you "need" (though be aware it is writtenin terms of 5E);
https://www.fantasygrounds.com/forum...eed-to-play-5e Also note that when you buy a FG version of a Paizo product, you get the Paizo PDF for free (or get a discount of the PDF price fromt he FG product), but that assumes your purchases qualify on the Paizo store, which I believe Amazon does not.
You can see demo's of FGU dynamic lighting on the kickstarter page. There are 2 relevant to LOS demo's. Imo it will be much more useful than Roll20's dynamic lightning (given the terrain feature blockers) but will not yet have light sources.
I would suggest you consider FG now, and then get the upgrade when FGU comes out. Plus if PF2 is your driving factor, no point in investing elsewhere if FG is what you see as superior in the near term (end of year).