Official comment
The DDJ-400 is the replacement for the DDJ-RB, which is a rekordbox product. The SB3 is a Serato DJ product. If you want to use either of them with Virtual DJ, they will both work as they're both MIDI devices.
Both of them use ASIO drivers, which is needed for multiple channels of audio for the master / headphone outputs. WASAPI or WDM drivers are not recommended as they only output a single pair and don't provide the necessary functionality.
As for the pitch fader, it's really up to whatever you're comfortable using or familiar with. Personally, I've never had a problem using the sync button to match tracks (why not use the tools available to you?), and manual changes are accurate enough on either unit.