Yes...you might need an adapter but is unlikely. 

Yes and no. Using motion detection it doesn't work through a window. However.... using the timer inside it you can record through a window using it. How? Set the timer to record 4 minutes every 5 minutes for 1-5 hours or whatever time you need it to record for. This is what I do- just make sure you have a SD card with enough memory for the videos- I use a 32 GB SD card, I use it though a window as a security camera for my car....I live in an apartment so I can't hard wire anything and this works great for what it is. 

The nd1000 filter can work with Fujifilm X series camera 

Dear customer, it could support a fujifilm x-t4 and a 400mm lens. and an adapter is needed to use the long and heavy telescope lens. 

Yes, the tripod fits your FujiFilm X system camera