For me, i am travelling most of (western) europe.. over a course of about 4 months..about 23 different cities.. So from what ive read, a Global pass would be best? Does the "21 day" pass mean you use it 21 different days within any certain period of time? or 21 consecutive days?.. Would it be cheaper for me to do 2x "10 days in 2 months" passes? I really dont understand which pass to get...???
You should post this question on the Transportation board. Also, you can contact the RS Rail Department through their link at the top of the Transportation board.
Since you'll be traveling for four months, be aware of the Schengen Rule. You can spend a maximum of 90 days in Schengen countries in a 180-day period. You'll need to spend a total of 30 days in places like the UK and Eastern Europe in order to limit your time to 90 days in Schengen countries.
I read your proposed itinerary (below). Be aware that Great Britain and a couple of your suggested Eastern European countries are not included on the Eurailpass. You might begin or end your trip in England-Wales-Scotland, using a separate pass or cash for those trips. Then travel to Ireland, begin using your Eurailpass there and fly to the Continent. Use your Eurailpass in the Eurail countries. You could save Italy and the countries not on the pass for last. Pay cash for point-to-point tickets in these countries. Italy is a Eurailpass country, but for most trips it won't cost much to just buy tickets as you go. Be sure to read carefully the info on "railpasses" located on the tab above. Only you know which pass will work best for you; if money is no object, go with the Global Pass and enjoy maximum flexibility. If you are young enough, buy the youth pass.