Does iPad air include a new bluetooth programme which isn´t compatible with my older devices (4 years old) ?
At this time, it limited to other devices running ios 7.x.
mobile Nokia N8
You going to have to install more software on the N8. I suggest you try dropbox. You can look for some protocol that both iPad & the N8 support.
There are lots of ways of moving files.
A simple and popular way to copy files and share files amoung your devices.
https://www.dropbox.com/
Using iTunes to transfer files:
http://support.apple.com/kb/HT4094?viewlocale=en_US&locale=en_US
Files Connect -- The swiss army knife of remote file connect
https://itunes.apple.com/us/app/files-connect/id404324302?mt=8
iExplorer -- " iExplorer's disk mounting features allow you to use your iPhone, iPod or iPad like a USB flash drive."
http://www.macroplant.com/iexplorer/
Windows File server
http://itunes.apple.com/us/app/filebrowser-access-files-on/id364738545?mt=8
"In education and business users increasingly expect to be able to access their data anytime, anywhere and from any device."
http://www.minnow.it/
Configure WebDave on your server.
This thread has good info.
https://discussions.apple.com/thread/3708341?tstart=0
How to transfer files from your iPad to your PC with iPad to Computer Transfer
http://www.iphone-mac.com/how-to-transfer-and-sync-contents-from-ipad-to-pc.html
More ways to transfer files and access Word documents:
https://discussions.apple.com/thread/4044866?tstart=0