Whats wrong with the hashrate?
I am not sure why it shows up like that, but there is no more hashing at all on the network so the number is invalid anyway.
The "difficulty" is apparently 4294967295 but I'm not sure why. I will have to ask Roman. If it is 4294967295 though and the network gets one block every 15 seconds (default delegate staking time) then if it were hashing, it would need 68.27 MH/sec.
The difficulty is 4294967295 for every proof-of-stake block, yes. The reason is that the winning blockchain isn't the one with the most blocks, but the one with the greatest cumulative difficulty. I wanted to make every POS block way more important to the blockchain so that nobody could re-mine a part of the blockchain with more proof of work, and then cause the blockchain to switch to that, which would have been easy to do if I had done something silly like make the POS blocks only worth 1 difficulty.