This is correct provided that the sound card and the sound cards drivers support “multi-channel” recording.
Unfortunately there is little information available about which sound cards will actually work with Audacity for multi-channel recording - I’ll attempt to explain why:
There are two types of drivers (software that allows the computer to recognise and access the sound card) that may be used - ASIO drivers and standard Windows drivers.
The main problem is that most (all?) multi-channel devices are supplied with multi-channel ASIO drivers, but ASIO drivers are licensed in a way that prevents Audacity from being shipped with ASIO support. This means that on Windows, Audacity must use standard Windows drivers (WDM drivers), but while some multi-channel sound cards are supplied with full multi-channel WDM drivers, some have limited functionality when using WDM drivers. The manufacturers rarely (never) say if the WDM drivers for their sound cards support all features of the sound card (including multi-channel recording), or if they only support basic 2 channel in/out. This means that we rely on information from other Audacity users to say if their multi-channel sound cards work with Audacity or not.
There is some information in this topic about multi-channel sound cards: Multi-channel Recording in Audacity
For people with multi-channel sound cards that cannot record multiple channels with Audacity, the sound card is usually bundled with software that does work for multi-channel recording, so they can use that for the recording. Once the raw tracks have been recorded, the tracks may then be exported in WAV format and Audacity can import these files for editing.
No it can’t. The PV6 USB mixes the inputs and allows recording of no more than 2 channels at a time.
This means that you could have:
Vocals => track 1
Guitar + Bass => track 2
or any other combination, but only two tracks.