Advertising by Tzedakah Organizations: Promises of health, nachas, shidduchim and parnassah – false advertising or needed yeshuos?

Do the halachos and secular laws regarding false advertising apply to organizations raising tzedakah?
Are promises by the charity a permitted form of advertising?
Should a charity require a minimum payment in order to get a beracha?
Is it better to daven for yourself, or have someone else daven for you?
Do the ends justify the means? Can puffery/manipulation be used in ads for the purpose of raising tzedakah for the genuinely needy?