If you need only view a PowerPoint document, you can use almost any iOS app that displays documents (including Apple’s Mail and Safari). iOS can natively display, though not edit, PowerPoint (.ppt and .pptx) documents—but it shows them as a continuous scroll rather than as individual slides...
Only one normal iPad backup is kept by iTunes, it's actually an incremental backup in that only data that has changed is actually backed up. The other backups you see listed for your iPad, that are time/date stamped, are backups from restore points. These backups are not overwritten. Unless you...