Broadwell will be supported by the new 9 series boards. I believe it will also shrink to 14nm instead of Haswell's current 22nm.
As rgd1101 said, the i7's will have 4 cores with hyperthreading. And from what I've seen even Skylake will only offer 4 cores for the consumer market.
If you want 8 true cores you're better off looking at Haswell-E, or Broadwell-E.
As for the prices, they'll likely be around the same as current CPUs. This is at least the case for the Haswell refresh, and has been the same for intel over the past few years. I expect broadwell to follow the same pattern.
Broadwell should launch late this year, with Skylake emerging in mid-late 2015. The Haswell refresh is expected in the next month, with the Z97 boards being on sale next week.