Welcome. If you can make something run at 8000 fps, you certainly have know how that would help!
Resolution is basically a factor of how much is one willing to pay for the sensor (camera), how fast the sensor needs to be (slower = affordable), and the sometimes overlooked optics. I have been doing 8 and S8 with 24MP camera (slow, very slow = less than $400 camera), but the results are great. Working on another built that will use less resolution, hope that a bit faster, but since I do not have the budget, it will still slow.
Yes. I built a variable current one which is essentially running DC. Here is the info.
Some in the forum have reported issues with sensors and light, and have taken the workaround of flashing the illuminant (the led lamp). While technically not DC, as long as the LEDs are fully on while the camera is capturing, that’s another approach. Think of it DC while the shutter is open, off while is closed. There are some advantages of this approach, such as less heat, and using more light without overwhelming the sensor. There are also some shortcomings too, such as white LED phosphor takes time to get to full illumination and these also take time to turn off, and it becomes harder to do dimming if one seeks to control the intensity of the light.
DC is the best approach, as long as one can manage heat and stay within sensor limits. However, the higher the speed, the most light required, the likelihood of overwhelming the sensor resulting in smearing.
Hope the info helps.