Help Planning Germany Trip?

So here's what I have so far:

1. Sept 13 fly to Frankfurt via KEF, Iceland. Breakfast in Iceland (win!) and lunch in Germany (woo!)
2. Sept 14 is when we land in Frankfurt.
1. I need a suggestion of a hotel in Frankfurt
2. I need to know how to get to the train to Dusseldorf that will take us to Berlin
3. We plan on renting a car in Berlin and heading south.
4. We already have a hotel booked (and paid for) in Munich for Oktoberfest. So that's 3 days, two nights of 'fest (and you can walk to a castle from our hotel and it has free parking and free SKY TV so...that's cool (TV in English without subtitles).
5. I'd really like some suggestions on hiking, breweries to see on the way south to Munich.

Flying out of Frankfurt on the 24th of September, it leaves in the afternoon and gets in to Boston for 6:30pm the same day.

Thanks for any help you can provide! For those of you that have been...I'd love to hear from you!

We've rented cars in Europe 4 times before so it's not a big deal to us (only in Scotland where it was a standard and you had to shift with your left hand--yikes).
(photo source, Lonely Planet, click for page)

Webcams

I know there's webcams all over the world where you can look at things that interest you.

I checked out this one that came in the Icelandic Tourist Board's newsletter. I really wish all e-newsletters were like this one. It's always informative and sometimes even humorous. Since it is winter a much of the focus was on things like the Blue Lagoon. Now I've only had dinner there but it's a pretty neat place. The spa experience there sounds like something you will not get anywhere else. A floating massage? Interesting...

I am treating myself to the spa for my birthday. I normally do not get pedicures in nice spas because the pedicure with the hot stones for under $30 always does the trick at a place in my town. I'm going to the Aveda spa/salon in Bedford (where I get my eyebrows done--love that place). That should be nice because I always like my feet to look good in Centergy class. Anytime you have to show your feet in public (for me 2-3 times per week) you can't have them looking gross.

Do you have a favorite spa or spa service? Is there a webcam that you have bookmarked that you enjoy looking at (I mean something more exciting than the Cape Cod Canal one)?