Just one more question - is it possible to copy an existing blockchain into a new crypto currency that uses a different algo?
Couldn't find anyhing about that, but someone claimed it was possible. Wouldn't the block hashes be different with another algo?
Such a construction typically involves using the original algorithm for old blocks until a certain crossover checkpoint and using the new algo on all blocks afterwards. So the blockchain that you import will need to be verified by clients through the use of the original algorithm, but you can enforce that any blocks after block-height X require the new algorithm.
It's not possible to change the algorithm used to verify old blocks unless you redo the proof-of-work on all these old blocks with the new algorithm.