iPod Touch File browser

[JJ!]

Hi,

I've got the latest iPod touch.
And I would like to install a file browser/viewer without authorizing the iPod [need to do it on multiple iPods. 10++]
They will be given away to customers who will probably want to authorize the ipods later them self.

What would be the recomended steps to add a file-viewer application and some documents ?

I probaly need to jailbreak those iPods ??
What simple file-viewer's are there? I've found "Files", "AirSharing" or "mobilefinder"(not sure it will work for 2.0)
Could I copy a bought apliaction to an other "jailbroken" iPod Touch?

I'm interested in any experiences and solutions!

Cheers, JJ