So Im going on backpacking trip to mostly Western Europe next year (May- Late September). I know its a little early but I love to plan early and feel very prepared.. But I would really love some advice from people who’ve already done it. I’m going alone for the most part by then I will be 21, turning 22 while im there. My brother will be going with me for the first couple weeks. He is only staying while Im in Ireland and then flying home when I leave Ireland. Ive already got guidebooks, after reading alot of them I found I liked Let’s Go Europe on a Budget and Lonely Planet Europe on a budget fit me, and my trip the best… But I have alot of questions starting with TRAVEL…. I do not mind spending 1000-1500 for my flight but I want to know what is about average, whats more on the cheaper side and whats more on the expensive side. Im flying out of Jacksonville, FL to Dublin, Ireland. I rather spend a little extra money to fly out of where I live and fly directly into the closest airport to Dublin. Also.. I definately am going to get a railpass but which one? I know my internary but how many days would I want to get… I do not know how many days I would need to travel from here to there and what not.. Would it be cheaper to get a railpass for just England and another one for the rest of the trip.. My brother and I were thinking about renting a car for the Ireland part.. but im scared about the driving difference.. Also in the big cities whats the best passes to get for inner city transportation for the cities im staying in longer, etc. Whats the best way to cross the water from Ireland to Scotland, London to Amersterdam, etc. Also after you read my itinerary please feel free to give me any advice on the cities im going to.. Only the major cities like Dublin, Paris, Rome, etc am I dead set on all the little ones here and there are just ones Ive read about that have interesting sites, etc… So feel free to let me know which cities are better, which ones I may want to skip out on, maybe cities I might want to stay a little longer or less in.. Im  very flexible on my trip. Also a little about me to help you in your advice.. Im a big history and museum girl… I rather spend long hours in line for museums adn such the go to the beach… Im not doing any sport such things as skiing or anything like that.. Thankyou for any help you can give me.. I really do appreciate other opinions who have already been there and done that. Also any websites you can give me to do with anything and everything things to do, travel, packing, etc… And do you recommend atleast talking to a travel agent or maybe trying to book everything on my own?
Here is my itinerary.. It may change a little this is just the right now kind of thing:

City/How many days im staying..

Fly Into Dublin, Ireland – 4
Sligo, Ireland – 3 (including a couple day trips)
Galway, Ireland – 3
Aran Islands/Cliffs of Moher, Ireland – 2
Limerick, Ireland – 1
Cork, Ireland – 3 (day trip to Blarney Castle)
Glascow, Scotland – 2
Iverness – 2 (I may cut this out bc its really out of the way depends on how bad I want to go to Lochness when I get there)
Edinburgh – 4
New Castle-Upon-Tyne, England – 1
York, England – 1
Manchester, Englad – 2
Liverpool, England – 2
Stratford-Upon-Avon, England – 1
Oxford, England – 2
Cambridge/Ipswich, England – 2
London (day trip to Cantebury) – 4-5

Going from London to Amsterdam
Amsterdam- 4
Brussells, Beligum – 2
Paris (day trip to Versailles),France – 4
Bordeaux, France – 2
Granada,Spain – 1
Cordoba, Spain – 1
Madrid, Spain – 2-3
Barcelona, Spain – 2
Toulouse, France – 1
Marseille, France – 2
Nice or St. Tropez, France – 1-2
Milan, Italy – 2
Florence, Italy – 3
Rome, Italy – 3
Naples, Italy – 2
Pompeii, Italy – 1
Venice, Italy – 2
Berlin, Germany – 4
Frankfurt, Germany – 2
Munich, Germany – 2- (Oktoberfest should be going on so I may stay longer.)

Also would it be cheaper to fly out from there or to go back to Dublin?