Church Discipline, Final Judgment, and Tithing

Jehovah's Witnesses keep coming to my house. Should I talk with them? Our pastor was involved in immorality and stepped down for a season. I'm not sure if I can trust him now. Was he gone long enough? I'm worried about the final judgment, because I haven't done anything good. Our pastor says we have to pay tithes to the home church (and not another church or ministry) in order to be blessed. Is that biblical?