Transfer Word and pdf files between PC and iPhone
You have various options. You can use a cloud service like Google Drive or Dropbox or Microsoft OneDrive and that will let you access files there or save files to there on either device.

I'm not very familiar with Windows, but depending on the version of iOS you're running you may be able to plug it in over USB to your PC and use some program to browse the file system on the phone (on Mac I can use iFunBox or something like that, but I only resort to that in special cases). That would work if you don't have Internet access but you do have USB access.

I don't quite understand the other part of your question. Like any smartphone, an iPhone works best if it is online (cellular or WiFi). What you can do will depend on the app. You will be able to record notes and take photos and listen to music and whatever else depending on the app. You can't check new mail or browse the web of course though without Internet.