I have saved each project with it's own audio folder in it. I still have the old audio folder outside of the project files. Do I need it? and also the audio data folder?

Cakewalk creates that folder and it's the default when you export a project I do believe. I always change my pathways in Preferences/ Folders to my own mixdown folder. I don't generally store data of any kind on C drive.  So for me that audio folder is never used and I sometimes delete it. It really does no harm being there like many useless folders in windows.  There was also a Global Audio folder that was for the Projects Audio in the bad old days of none Per project audio folders. That made a huge mess for many people. 

a6strng
I have saved each project with it's own audio folder in it. I still have the old audio folder outside of the project files. Do I need it? and also the audio data folder?

It depends where your CWP is looking for Audio files.
 

I think it will also create that folder if you create a song but don't name it but I'm not sure...I'm a per-project folder kinda guy.