Not quite sure what you mean...'will my new traffic become my downloaded planes in FSX ?'
If you've just downloaded new planes, then no. FS does not automatically generate AI flights. All flights are 'programmed' in a file, sometimes referred to an AI Traffic file. It/they contain the 'flightplans' for every AI flight.
If you're unfamiliar with AI traffic files, download Traffic Tools v2.02 from
http://www.simviation.com/fs2004utilities1.htm. It's for FS2004, but the concepts described in the help file, 'Readme.htm', are the same in FSX....or... If you have the FSX-SDK installed, you probably have a similar document in the 'Traffic Toolbox SDK'.
If, on the other hand, you have downloaded and properly installed traffic packages (like those from WoAI) that include both aircaft and traffic file then they should fly whether you remove the default traffic file or not...
Dave
RE: your earlier ??..'Which one of suggested downloads are the best??'..
Depends on what type af ai traffic you're looking for. WoAI is a good place to start, particularly for real world commercial flights.
At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation. Igor Sikorsky
I intend to live forever....so far, so good. Steven Wright
You know....you can just rip up a to-do list.