1. What is the exact requirement to join a signature campaign?
At least become a full member, most BTC paid signature campaigns are acceptable ranks.
But when you become a Jr/Member rank, you can wear a signature but the text is limited.
He will have to wait a long time for his account to meet the conditions of the signature campaign. But even Newbie can participate in the bounty of the company and receive new altcoins as a reward -
https://bitcointalk.org/index.php?board=238 But for this, he will need to have accounts in various social networks.