1. Can be. Any hourly form most likely will be more proffitable.
1.1. Everything depends on what YOU are GOOD at. Some find MTTs easier some find daily 15$ (or sort of that) easier to do
3. when needed =)
Over a couple weeks to around a month, cash games are more profitable. Over a very short span of time or long span of time, this is where possibly tournaments can outdo cash but the issue is if you gotta pay rent that month etc.
Cash games are for players who understand card probability very well, tournaments are for players who understand human psychology very well.
Poker requires you to understand both, the one you end up excelling at is depending on math brain vs psychological brain.
Cash games MAY be profitable, but recently I have come to conclusion that tournaments are much more stable, from BRM point of view.
In cash games there are huge downswings. While playing exclusively tournaments, it is far less so, because you can lose only buy-in(s). True, it is more difficult to make money in the short run, but when you win in a tournament, you win big.