Nixon was his political enemy, big-time. Felt hated Nixon, which is why he went after him on the Watergate break-in.
He should have proceeded to let courts of law try crimes that were committed. Felt should have kept his mouth shut. The burglars were arrested and charged along with those who conspired with them, two of which were former CIA operatives.
Hunt and McCord had been heavily involved in black ops against communists. Nixon was very worried about that and the fact that they were blackmailing and threatening to leak sources and methods in the Cold War if they weren't paid off.
And no, Felt never leaked anything about the Dems, nothing about LBJ's "enemies lists", or JFK's affairs with mob chicks, etc. etc. etc.
You are correct. Leslie Stahl was on Hardball tonight (incidentally, she revealed she was dating Woodward at the time) and she pointed out admiringly and in a tone of agreement that Chris then also adopted, that Felt had made statements that conveyed a sense that he considered the Nixon administration as Nazi-like.
Yes, she used the word "Nazi".