How To Import Several Recorded Project Files With different tempo n Style to a Single Proj

If you mean your song changes tempo throughout it's length it's easy to either set this up in your project, or to export the audio from your sub projects and import into the "Master"

If you mean you want certain tracks to have a different tempo but playing at the same time then Sonar can't do this - the only workaround i can think of is to do the export > import suggested above

But seriously, if it's the first situation, you are much better off doing this inside your master project - inserting tempo changes is ridiculously easy