General questions about C:\ProgramData\Microsoft\SharePoint\Config files?

I've cleared out the xml files and updated the cache.ini when running into problems before, but I'm not sure exactly what these files are.

I see two folders:

• one contains .persistedfile files
• one contains cache.ini and xml files

I know that they're associated with Timer Jobs.

Can someone tell me

• exactly what do these folder names correspond to?
• what do the files correspond to?
• do they belong on all web servers in a farm?

Thanks,

Scott