They switch automatically normally, but if for some reason you have a couple of devices working you can use the remote to switch it. You only need to know which port number corresponds with which input device.............
Should do. B&Q sell a version if you're desperate and don't want to go far (assuming they have it in stock)
http://www.diy.com/departments/smartwares-2-way-hdmi-selector/571880_BQ.prd
Have you got a splitter or an HDMI switch ? You need the latter to switch between sources - the former is to allow a source to be replicated on two screens.
Examples :
Splitter -...