No. Bitcoin uses its own protocol. Raft could not be used for a secure cryptocurrency bevause Raft does not handle byzantine faults[1]. It assumes nodes are not run by malicious actors and messages sent are unaltered in transit.
True. Though in tradeoff it has massively increased throughput. I'm always frustrated when I see blockchains recommended as a solution for a consensus problem in anything but a zero-trust scenario
Even in a zero trust scenario, you need a majority of nodes to be good faith, non-colluding actors. Even anarchy breaks down in the face of unequal power.