In answer to question 2, when we financially support a ministry we receive God's promise of blessing us and seeing that all our own needs are met. It ties in with the law of tithing -- trusting so completely in the Lord and giving him the first of the firstfruits, etc. When we trust so completely that he comes first before looking to our own needs, he will pour out a reward so large that we cannot contain it. That is his promise.
I'm not sure that I know anyone who is really demonstrating this. Even the most generous still seem to struggle financially, so there must still be an element of self-interest involved in some way. I know it is true for myself. God's promise of reward would make everyone millionaires if their giving was done the right way.
But, being human, most of us can't do it. Even if we don't realize it, we give in order to get, rather than giving just because we love God and recognize that everything is his to begin with. When we tithe the first grain or lamb or 10% of our paycheck, we are only giving him back what is already his. We give it back for two reasons: 1) as a way of thanking him for taking care of us; and 2) because he has commanded it.
It is only our humanness that makes us question who we are giving it to and whether they will use it correctly, etc. It is humanness that makes us want to receive something in return for our giving or to receive something from the partnership. What we all fail to recognize is that we don't own anything to begin with.
I wish I could remember all of this when I pay out my tithes.