i wouldnt reccommend buying fpga board if you only want to mine bitcoins but if you want to learn fpga development i guess you would already know what you want
also pretty decent programming skills and good understanding of electronics are a prequisite
You almost nailed it. I have the coding skills and I do a lot of embedded development, mostly with PICs but also H8 and the like. I never used FPGAs before and I've been waiting for an excuse for a long time now, so bitcoins might very well be it.
I have a pretty simple understanding of electronics, but I do have people

So if I had to jump out of a dev board I could, and in fact would have all the expertise and industrial equipment available to me to do a full hardware implementation from scratch, but that obviously comes with an extra cost.
So, yeah, I *should* already know the answer to these questions if I had done my homework, but it's hard to keep up with everything and the bitcoin community has been the most helpful I've ever met... ever!
maybe focus on the price and secondary featureset of the board rather than cabability for fast bitcoin mining, you are not going to get rich quick with that anyway
i bought
Basys2 from digilent, should be great starter kit for very good price if you are a univercity student, you might want to take a look around that site, they have lots of Xilinx dev boards, take a look into your wallet and decide what you can afford. most people say its more important to get cracking hands on with the hardware than to spends lots of time selecting THE board, you will probably buy some more capable board later on anyway