Bridge is deprecated. While it can still be installed, it rarely offers acceptable performance.
Making VCV talk to another music application is still a messy process (I have a thread about making it talk to Reason on Windows).
Host will only allow you to embed a VST (and not AU) within Rack - not the other way around. The upcoming VCV for DAWs will work the other way around, but no release date is set yet.
For now, your best bet is to use virtual loopback MIDI and Audio drivers. Virtual MIDI is built into OS X, and it seems Blackhole is the most popular audio one.