iPad app to access Mac files?
Answering this 


  Is there an iPad app that that can open Mac files over WiFi on the
  iPad?


I bought a app called Files Connect on my iPad, I use it to access files over the Network to access shared folders on my Mac using my iPad and iPhone. It is universal app for iPhone/iPad.

It works also with Windows PCs, Dropbox and other services.

You can also use it to access your iPad files using the Mac/Pc (opposite way)

I bought for $5, This is looking too much as a ad (I'm not related to this company), so read description for details. 

http://itunes.apple.com/us/app/files-connect/id404324302?mt=8