That is not correct. Take a look at
Amazon Fire TV - XBMC
Keyboards, mice and game controller are working. But unfortunately no support for hard drives and USB sticks.
You can't. Slimport switches between USB or HDMI. USB and HDMI is not possible at the same time.
You'll find more details here:
AnandTech | Hands on with the Analogix SlimPort microUSB to HDMI and VGA adapters