1. Out of the listed scientists I chose Thomas Malthus. When researching him I found a piece of Charles Darwin's autobiography, in which Darwin stated that his idea of natural selection came into being from his readings of Malthus's "Essay's on the Principles of Population." Considering that reaing Malthus's work lead to the creation of his theory, I would venture to say it was a positive influence.
Link: http://www.ucmp.berkeley.edu/history/malthus.html Title: Thomas Malthus Author: Unknown
References used for site (provided for legitimacy): Milner, Richard 1990. The Encyclopedia of Evolution, an Owl Book, Henry Holt and Company. New York
Futuyma, Douglas J. 1986. Evolutionary Biology, Sinauer Associates, inc. Sunderland, Mass. Glass,B., O. Temkin, and W.L. Strauss (eds.). 1959. Forerunners of Darwin: 1745-1859. Johns Hopkins Press, Baltimore. Bowler, Peter J. 1989. Evolution: The History of an Idea. University of Califonia Press, Berkeley. Wood, John C. (ed) 1986. Thomas Robert Malthus: Critical Assesments. Vol II. Croom Helm, London.
2. Thomas Malthus, believed that struggles for life ended and began with over population. He began his research around a time where his country, England, was in poverty and many lower class produced more bodies than they could properly take care of. He believed this was the reason for God and that God would prevent man from being lazy. Darwin did not agree as to the reason and also later introduced more reasons to what is now called natural selection. In rough terms Malthus opened the door for new discoveries made by Darwin and Wallace.
3. The point Malthus touched on most was "Who gets better access to limited resources," although he focused only on humans, this was his point it seems in my opinion. He believed the rich had more resources, but the poor were reproducing more than they could deal with and this threw the whole country into poverty, he believed this to be god's work. He agreed that these led to some sort of selection, but he believed it to be spiritually based. As for what Darwin took from this and if it was positive or negative that is a matter of opinion, I can see how it might go both ways, but I think it was far more positive than negative. Yes, Malthus was incorrect in who he believed was the cause, we have grown scientifically and now know the cause as not a who, but a what. Darwin did build from what he read of Malthus's work and that I believe over runs the disagreement as to cause, because if we truly wanted to argue it, it is a matter of opinion. Some refuse to believe that it could be anything but god and some see it for what it truly is.
4. I believe that perhaps eventually Darwin could have come to the same theory without reading Malthus's work, but it would have been rather delayed. Especially considering how nervous he was to fight against all his country had known and followed until the moment he shared his discoveries. Seeing someone else starting to make similar conclusions to his own helped push him to say what he thought and knew. Perhaps if not for Malthus, Darwin may not have published his theory, but he most certainly would have still come to that conclusion eventually.
5. The Church made Darwin very nervous to publish his book, he feared what damage he might cause by publishing his theory, which went against all that was believed at that time. He was very brace to publish his theory and I believe he felt relieved when he finally did. In the end his fears were for nothing because they let his final resting place be in a church. I don't imagine if they had been angry with him for his beliefs, that this would have been allowed.