Yes you can bring in your own PDF files, in fact you have to because the app doesn't provide PDF files, it just manages them. You do however get the chord charts that you can transpose that are available here: Invalid Link Removed as a PDF that you transpose to the key that you need. iGigBook also includes indexes to over 60 different popular fake books and real books making it easy to find tunes in those books by using a search that checks each book for you, great for jam sessions or taking requests.
You can create a set list, sort it alphabetically, rearrange the items, and initiate playback of tunes in your music library that match the title of the song in your set list. You can also send that set list and optionally include the charts as a PDF attachment to your band members.
There's also another app, iGigBook Pager, that you can use with your iPhone or iPod that allows you to turn pages hands free on your iPad.