Can the cables be extended using a VGA extension cables?

I don't know how many pins in your extension are connected and are end-to-end, but if all the pins are there and all are wired straight through, I would guess so, as long as the extensions are plugged into the KVM box FIRST and their special VGA/USB combo cables are plugged into the extensions. You'd be basically extending their socket, then plugging the adapter cables into the PCs.

The kvm doesn't need a usb input from the pc? i only see vga inputs on the box?

The cables are not symmetric. The end with only the VGA connector plugs into the KVM switch and the end with both VGA and USB plugs into the PC. The end with only the VGA connector that plugs into the KVM switch uses extra pins on the VGA connector to carry the USB signal. This is a proprietary cable and can NOT be replaced with a standard symmetric KVM cable (ie, same connectors at both ends). Steve Clarke's answer (on another question) claiming that standard cables can be used is WRONG -- sorry. Seller: Please let us know if it is possible to buy replacement cables and how much they cost, or, alternatively, please provide a pinout diagram for the KVM side of these cables. Thanks.

Does it work if I have one computer running on Window 11 and one computer on window 10?

Yes, it works for me. I use it to connect to a server, windows 10 & 11 to one at a time to the same screen computer. It allows me to swap to the computer I want to work with. It will swap a USB port also so a wireless keyboard and mouse will work. It does not swap the speakers outputs or sound card connections. You may be able to use the USB port to do sound. My switch has 3 USB ports on it.

Does this carry audio signal??? Thx!

All it does makes it easy to switch three USB connection and a one VGA monitor to different computers. VGA does not carry sound. It may be possible to use one of the USB ports to transfer sound. There is no 3.5 plug to transfer sound inputs or outputs. I looked into it and you may be able to use a USB bluetooth out put device to plug into this switch and it will swap to every computer as the monitor swaps . My blue tooth mouse switches with the monitor.