[Matth]

The router is the far better alternative to using Windows internet connection sharing - which would requre one PC to act as the server - with a router, the router is the connection server, so you don't have to leave a particular PC on.

Depending on the router configuration, it may be that certain dervices are dedicated to one PC, such as videoconferencing, though with most setups, it would be possible to enable any PC to call out, but only one to answer.

Wireless is generally robust (actually, if there are errors, simpler protocols will have to be able to tolerate them, while higher level protocols have their own checking and retry), though care needs to be taken in securing it, or you may end up with other people joining your network!

Streaming audio/video normally used the "unreliable" UDP protocol, and is expected to glitch momentarily on lost/damaged packets.
File transfer, web browsing etc. uses "reliable" TCP, where all packets are accounted for, and resent if their loss is reported (NAK) or if their arrival (ACK) is not reported.