Once installation is complete, You can remove the USB stick?

When the installation completes can I remove the USB stick from the apple tv?

Then is that it in terms of needing a mac? Can I then just play all media content either wired to the apple tv or on a network drive without needing to do any conversion?

Many thanks in advance

Once the patch completes the installation on the AppleTV, you unplug the AppleTV and unplug the USB drive too. The AppleTV always defaults to the USB drive first when booting, so if it is always plugged in, you will never see the AppleTV boot properly. As for the needing a Mac, that is only for creating aTV Flash. The media you play can be on an external drive, PC, Mac, or NAS. The ability to play the video file depends on how the video file is encoded, MPEG, DVD, AVI, H.264, etc.