It assumes no malicious agents. If you're malicious you can take control over everything with a single message (advertise being the leader of the next term).
Raft cannot handle Byzatune faults by itself. There are variant algorithms that can.
Paxos is a family of algorithms of which Raft is a member. You can change Raft in various ways but then it's not Raft anymore, but it can still be Paxos. So of course Paxos can "do more".
No, Raft is mostly for learning the basics of distributed consensus afaik.