So basically you are talking about a cryptocurrency charity fundriser campaign.
I think that most of the cryptocurrency users are greedy and they won`t donate to charity projects.
Are the "small,periodic contributions"going to be mandatory or no?
I like the "voting" concept.Such a charity project should be more democratic.
A crowdsale will do the work.Every contributor will receive a token,which gives him one vote.
The more tokens you own,the more influence you have about where and for what the funds should be used.