Enter your VST folder in Options > Preferences > VST Effects > Default VST search folder. Vegas will find them when it starts.
In mine I have "C:\Program Files\Vstplugins\". In that I have all my 64-bit VSTs. If you have any old 32-bit VSTs that are not available as 64-bit version then you can put them in a subfolder of that folder and they will still get scanned.
Reverbs are subjective, Lots are available... free and otherwise. Search.. IMO, one of best sounding 'free reverbs' I've come across is the Ambience reverb by Smartelectronix.
Otherwise, the digital Lexicons were always a standard in music recording.