What is the threading of the microphone mount? And can it be attached to a boom arm?
The thread size of the mount is standard 5/8". To attach the mic onto a scissor arm stand with a 3/8" threading, you need to screw the 3/8" to 5/8" adapter that comes with the FIFINE K690 microphone package to the mic mount.
Which shock mount and pop filter fit on the FIFINE K690 mic?
When it comes to a weighty microphone, a shock mount is less important. The key to having less vibration is to use a sturdy scissor arm stand that can hold a microphone tightly. Thus, the recommendation is to spend the $20 extra on an arm rather than on a shock mount. But if you just prefer a shock mount, then you can consider something like the Moukey Microphone Shock Mount.
As for the pop filter, you can just find one on Amazon with the highest ranking or the most reviews. If you fancy getting a U-shaped pop filter, just buy one that fits a 57mm diameter microphone.