sha3. it uses keccak as one of its hashing functions. hell no it isn't scrypt based. yuck!

mix function? same as copperlark.

i've changed my mind(again) on the retarget. i'm thinking 600 blocks will be good probably. i read up about the yacoin retarget and wanted to try and use it but i think a standard retarget is the way to go.. for now. nothing is set in stone at this point. i'm veryflexible.