1. Don't change the format of the SD card. It should come standard as FAT32 (I believe) so leave it as that.
2. There's no way to force powershell to stay active, as you've set the windowstyle to hidden.
3. No idea about any special drivers.
4. Stay with GUI r as you are already using.
5. I use the encoder from the rubber ducky github.
6. Depends on the destination computer. 30s is a very long time. For me it's generally done in under 10s.
7. That just renames the file, it doesn't "convert" it. Using a different extension like .old may fool some AVs, but don't rely on that.
8. No, it won't need Java when it is running as a keyboard.