For an airdrop campaign, you could launch it after the bounty campaign, to attract new investors.
Yes signature is part of a bounty campaign, but airdrop is frequently part of a bounty campaign too. By the way, signatures is one of the most profitable bounty tasks unlike airdrop.
Nope,these days developers are starting to reduce the trust from signature campaign to the social media campaigns and article making.because they have learned the spamming this forum has,and investors are not satisfied about the outcome from the forum posting.