I'll start the ball rolling... pack light. Take a 21-22 inch roller bag and a laptop type shoulder bag. You seem to want to hop around a lot and the last thing you want is to be dragging a pile of luggage.

I suggest you beg, borrow or steal a guidebook or two. One of the "best of Europe" types might be good for at least part of your trip. Also a guide of eastern Europe. For me, part of the fun is exploring through guidebooks. They will have all or most of the information you'll be needing, including hotels in all categories, transportation options and schedules.

You're covering a lot of territory, and it's hard to give advice when you are considering so many places.

I think you need to narrow down your list. You've got 10 countries in you 6-7 week trip. That's a lot of moving around. Also if you trim it down a bit it will be less expensive. Because it costs money every time you move place to place, so stay a bit longer in less places brings down cost without sacrificing anything (well except seeing a bazillion places in a short period of time).

The eurail pass question always comes down to a matter of math. To figure out which, if any, will save money, you first need to know where you're going!

I personally love Switzerland but it's an expensive country generally speaking. So if budget and time are both concerns, might want to skip it this trip.

Not sure from your post what type of visa you will have - but you may have trouble entering if you don't have a return ticket. Esp if you are traveling casually/backpacking immigration officials are often more curious about what you are doing there, for how long and if you have the funds to support yourself.

Also - just getting a random one-way flight back can be extremely expensive. It might be safer - and cheaper to get a RT ticket and then pay the change fee for the return portion when your plans are solidified.

Thanks for the responses everyone!

I'm actually in Seoul, South Korea at the moment on a business internship so I've already packed as light as possible for Winter haha. I'll most likely be packing and sending something things home as it'll be a bit warmer in March in Poland/Europe.

As an Australian citizen, I don't need a visa for the EU so a single ticket shouldn't be a problem for me, fingers crossed!

I definitely want to do the primary countries I listed - they're a must! The other countries (which back the 10) are optional given time and money. I've been recommended by many people to get a Eurail even though London isn't included, there are heaps of other cheap flights and trains to London.

Any other thoughts??

If you want to go from Poland to Hungary, Germany, Czech Republic I think the most convenient is a train. There are some connections between major cities (like Warsaw or Cracow)and the capitals of those countries. Be aware that the Polish trains are sometimes late There is also a bus company called 'Eurolines' as an alternative. Of course you can travel by plane, but it's not for a budget trip.
If you want to get to London you can try 'Ryan Air' - it's a budget Irish company. They are not luxurious at all, but I have flown with them many times.

The countries a recommend is Slovenia and Estonia. I love them

If you want to know more, visit my blog about the Carpathian countries (southern Poland, Romania, Slovakia, Ukraine) - I try to improve it every day:
http://geographers-eye.blogspot.com/