Need help with putting together a mountain bike
The first thing to note is that the frame has to fit you. Also, the frame and rear suspension should be known to be in good condition before you buy the frame as well - this is especially important for carbon due to its failure modes.

If you don't have experience with this [and it sounds like you don't, given Fox pretty much makes shocks for everybody], you should probably work on this with a bike shop since the assembly process will require tools you likely don't have (and even if you have the tools, it may require expertise which you might not have, such as how to cut forks to the right length). Local riders can also help you spec a bike which is appropriate for the type of riding you do (for example, full suspension may be unnecessary in your area making this frame a bad choice and certain types of forks may be popular among people in the area for good reason). 

Generally, when selecting a fork, you will need to match the headset type and the fork geometry to what the frame is designed for. This question has a nice answer which summarizes those things and as does this link. Obviously, it needs to be able to mount the brakes you want. 

As for selecting disc brakes, read some reviews on various models and choose one based on your needs. 

In any case, voting to close this question, since it is primarily opinion based, highly dependent on the type of riding you do, your budget and your location.