Not Ad hominem as it is a simple fact that David Manning twice did prison time for burglary.
An "Ad hominem" is an argument which says someone is wrong because of derogatory information regarding them. It doesn't matter what is the derogatory information, the salient point is that such information does not refute his argument.
For example, Suppose David Manning said "The Earth Orbits the Sun." An "Ad Hominem" response is "He is wrong because he did prison time for burglary." You see how the derogatory information has nothing to do with the accuracy of his claim?
So yes, your arguments are all claims of bad things done by David Manning, and nothing which actually proves he is wrong. This is known as an Ad hominem "fallacy."
http://en.wikipedia.org/wiki/List_of_fallacies