I don't use XBMC, so not sure about issue 1.
2. Look for option "Zap before stream" and un-check it.
3. Port 80 - for web interface and streaming recordings
Port 8001 - streaming of channels
Port 8002 - transcoded streaming of channels
Port 8003 - transcoded streaming of recordings
NOTE!!! Make sure you enable authentication for webserver AND streaming (two separate options) and I highly recommend you use non-standard ports for the outside connections. Many routers allow you to map an outside port to different internal port (ie port 9001 on internet will connect to port 8001 your VU+.) If your router does not support this, the default ports can be changed on the VU+, but it is not as easy as doing it with the router...
