Do We Make/Own These files?

No, we simply relay them on, most of our files are Gamerips that we distribute under fair use

Can I Use These For Remixing?

Absolutely! As the files are Gamerips you can use them to your hearts content and the ones that aren't you can use (with credit to the original maker)

Can I Use Soundfonts Natively in FLstudio?

No, You will need an external plugin, there are many out there, some paid, some free, do your own research, the one that I personally use is sforzando by Ploque.

What Is a SoundFont File?

A SoundFont File often distributed as .SF2 is a file that contains data for different Instruments/sounds, many older video games used them .