Iím sure all these questions have been asked before and I apologize for repeating them, but I suck at finding things.
Please start here: http://wiki.linuxmce.org/index.php/FAQ
Most here are very friendly and willing to help, but as you said, many of the questions you asked have been asked/answered before.
A quick recap:
wireless- no bad idea
webcam- check on the hardware section on the wiki- http://wiki.linuxmce.org/index.php/Hardware
tuners- number of tuners = number of decoders = number of separate tvs to watch shows on (generally)- if the streams need to be decoded that could be a different issue
game console- not sure about this
printer/file server- yes