1. Yes WICED can run on Linux.
2. WICED is an SDK that contains documentation, header files, libraries, samples and tools requiredto develop applications. It allows to access various fetaures of any WICED device by using APIs. You can refer the WICED Technical Brief
3. Your understanding is correct.
The OS supported in WiCED are: ThreadX and FreeRtos. You can find OS libaries at WICED-Studio-x.x\43xxx_Wi-Fi\WICED\RTOS
4.You can not run Linux on CYW43907
Could you please explain why i can't run Linux on CYW43907?
From my understanding, CYW43907 has a Cortex R4 which can support uCLinux?
Thanks for your support.
You should be able to run linux on 43907 but as of now it only supports WICED driver. If you want to use uC Linux on 43907, we might not be able to help you much in using Linux on 43907. You can choose other wifi chips which support linux from: IoT Solutions Guide