Yes, it is the same socket and will drop into any 300 series motherboard. No, it would not be worth the extra money, they are the same chips. The 8086k is just clocked a little higher, than the 8700k.
The 8086k is a binned chip, so it should be able to hit higher overclocks than the 8700k, so if you are really into overclocking, then it may be worth it. But for the vast majority of people, it is definitely not.