which external devices are supported by my chromebook c200?

Hi,

According to the specifications there is a HDMI port and 2 USB ports (1 x USB3.0 and 1 x USB2.0) and Bluetooth so you should be able to connect an external monitor to the HDMI port and a mouse and keyboard to the USB ports or the Bluetooth connection. The USB3.0 port is backward compatible so that you can insert (carefully) a USB2.0 plug.

You may find a marginal reduction in battery life with the devices attached so if you also connect the charger you should be good to go.

Perhaps you should look at a using a Bluetooth keyboard, mouse or keyboard mouse combination instead of tying up your USB ports so that they can be used for other devices, e.g a flash drive etc

Hope this is of some help.