My question is: Are there any tools to use a via USB connected android phone on windows/pc?
I'm using a analog headset and want to answer calls via the headset when my phone is connected.
A Phone connected through the USB, no.
But if the phone is instead connected through bluetooth to the PC, you can try to turn on HFP (Hands Free Profile) Bluetooth profile service from your PC's bluetooth stack. The only way I found this possible was from the BlueSoleil Bluetooth Stack Software where you can set the bluetooth to parade as a "headset" instead of "laptop/desktop" and hence your phone can connect to the PC thinking it is a headset.
However, BlueSoleil is not free and the evaluation version allows only 2MB worth of voice data packets in one connection after which the connection is automatically interrupted.