Yes, there is a 1/4" interface on the bottom of the stand, which can be directly mounted on the tripod 

Yes you can. In fact that is what I am doing right now. The one that came with the telescope was alright but the camera tripod I have is a Polaroid and works much better. 

Hi. Yes it is suitable , in fact , that's the very camera I'm using it on. It rather depends what you mean by 'fully'. The camera will not use any of it's auto features because the lens is totally manual , there is no metering and also the focus aids don't work. However , the camera takes pictures with a tamron lens perfectly well . Set it to 'M' on the dial and then set your own shutter speed and aperture . It will look a little dark through the view-finder ( at least it does on my 135 telephoto lens ) but the pictures come out fine . 

as long as the adapater has a standard 1/4 screw mount, it could be used on the tripod. 

Yes, the tripod can fit your FujiFilm X system camera