Does it still use the stock vram and power supply?
The DRAM ICs that make up the VRAM are not used when the F18A is installed. In my development 99/4A computer I completely removed the DRAM chips, which relieves the power supply a little. I *think* in the CV, only the DRAMs require the -5V and 12V, which means with the F18A you can replace the power supply with a single 5V supply (you will want to confirm this though). Yes, the F18A uses the system's 5V power via the same pins as the original 9928 VDP.
I noticed there are other parts mentioned for install. Is the kit complete With everything you need to get running without ordering various parts from china?
The F18A comes with a VGA pigtail and "PC" back-plate that you should modify and mount in your case to provide strain relief for the 15-pin VGA connector. For systems that have the original VDP soldered to the PCB, you will need to remove the VDP and add a socket yourself (the F18A does not come with a socket). No need to order a socket from China, they are easily available from suppliers in just about every country. In the US you can get them from Frys, Radio Shack (if you still have one in your area), Digikey, Mouser, JameCo, AdaFruit, SparkFun, etc.
You say the stock ribbon cable is in backwards in that pic. Is there a picture of the normal install?
grips modified the pigtail that comes with the F18A for a more custom fit. In the modification, the original 16-pin header was removed and flipped over, so it had to be plugged in upside-down from what would be "normal". I think grips made that comment to prevent confusion for anyone installing an F18A but not modifying their pigtail. The F18A comes with an instruction sheet that shows the proper orientation to plug in the pigtail.
The complete rf daughterboard can be removed and this will work as bypasses it completely?
With the F18A installed, the original video output will be dead. If you do not care about being able to reinstall the original 9928, then yes, the entire RF section could be removed from the motherboard.
For sound do you go off c88 and ground?
On my test CV I picked up sound from C88 and ground, and ran the wires to a standard "RCA" style audio jack. If worked fine, but there are probably other ways as well.