Please contact our customer service for replacement and support. 

The V50x comes with a skeleton case with a slotted rear door replacement, but there is no opening to allow plugging in an external mic. As a note, the sound recording, even while in the completely waterproof case, is better than I had expected. If you're not worried about moisture, there is a threaded tripod mount on the bottom of the camera and an adapter that will allow you mount the camera without using the case. 

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