the Apps for iPad/iPhone/iPod Touch can be used for a lot of things, depending on what you need. Apps are similar to "installed programs" for Windows users. There are Apps for writing notes, writing documents, spreadsheets... etc. and there are Apps for games, reading ebooks, playing music etc.
When you got your PC it did not have Microsoft Windows, or Quicktime Media Player or Anti-Virus or StarCraft 2 right? You have to install them first. Apps are are like that. Cooler than Windows though, Apps are downloaded straight from online and installs directly into your iPad with no puzzling installation procedures. Check out App Store for free and paid Apps.
And yes, you can still access IPF just by using your Safari Browser. Safari Browser is similar to your pre installed Internet Explorer on your PC.