Using Pst Mail is extremely easy. You can transfer pst files to your device, using several methods (iTunes, Pst Mail Sync, Dropbox, etc.). Once copied, use Pst Mail and all your messages will be available for browsing, displaying, replying and forwarding.

More information at Pst Mail Manual

Both versions of Pst Mail have the same functionality, although the lite version will only let you open 10 items per folder.

Pst Mail app requires iOS 4.3 or higher. It works with iPod touch, iPhone and iPad. When running on the iPad, it will make good use of the larger screen size.

Pst Mail has the same functionality on both devices. The advantage of using the iPad version, is a greater screen size to accommodate your emails.

Yes. Pst Mail can open any number of pst files. They will be displayed automatically in the first screen.

No. Pst Mail can open all pst files, regardless their size.

Pst Mail is able to read files generated pre and post Microsoft Outlook 2003 for Windows. It means it can handle ANSI (16-bit) and Unicode (32-bit) versions of the pst file.