yes airdrops and bounties are the simpliest way to enter in this world, you can earn by you effort without any investment
Yes, and it also encourages a lot of newbies to create multiple accounts and join airdrops.
Bounty Campaigns, airdrops, mining etc are some ways by which you can get some profit without any investment. But you must identify a good ICO for that otherwise your efforts will be waste.
But I would rather join Bounties or Signature campaigns because its risk free, as compare to mining or trading, high risk and sometimes low reward. Signature campaigns is the viable option to earn with altcoins, because all you have to do is join, follow the requirements and wait till the end of the ICO to get your rewards. Will only take a few minutes or hours of your day. But you will need to have patience as well because most of them lasted for more than 4 weeks and additional weeks to get your rewards.