which lenses to choose for Canon eos 7d

Hi guys,

I'm brand new to this forum and new to photography so I am trying to gain as much knowledge as I can before I go buy my first DSLR!

I've decided on the Canon EOS 7D because I want to take action shots of sports as well as attach a good telephoto lens to get great surfing pics.

Can anyone help me choose between these two telephoto lenses, I don't know what the difference is between them so you may need to explain it to me in basic terms!

I am a beginner but I wanted to buy the largest telephoto lens available, being the 400mm.

There is around $300 difference between the two but if the more expensive one is better, I would prefer to buy it.

I haven't bought any other lenses yet either, so maybe some suggestions on what size is most versatile would be most helpful.

I'm also planning on buying a fisheye lens.

Could someone please explain what is the difference between:

EF 100-400mm f4.5-5.6L USM

EF 400mm f5.6L USM

I've read that it's better to spend your money on good lenses and since I probably won't be upgrading for a long time, I'd like to buy really good ones right from the start, however I do unfortunately have a budget so buying one lens that's $6000 is out of the question for me right now!

Thank you in advance from a newbie!

Cheers ~ Kylie