IRS regulations allow clergy to preach about moral or political issues, as long as they dont favor one candidate over another.
Internal Revenue Service regulations forbid all tax-exempt, 501(c)(3) organizations including churches from promoting or endorsing candidates.
Absolutely. In fact many 501(c)(3) organizations are chartered specifically for the purpose of studying, promoting and advocating a particular social issue or concept. Planned Parenthood certainly is an advocate for abortion as PETA is advocate for ethical treatment of animals and Greenpeace an advocate for protection of the environment, etc. etc. etc. It would be positively ridiculous for any of these organizations to be muzzled and not be able to publish or promote their research and conclusions.
None are allowed to say vote for Candidate A or don't vote for Candidate B or support this party or whatever, but they certainly have as much right as any other Americans to express their opinion about any issue as being good or bad or neutral.