In response to your first two questions, I don't object to the view that the earth is very old.
For question three, I don't object to natural selection. Variation does occur, within kind.
For question four, we have no way of knowing for sure if there are outside limits to variation. Human experience indicates there are. There's no proof either way. Evolution assumes that over time accumulated mutations would lead to all the millions of species we have on earth today. This is basically the crux of the debate. I doubt that the massive number of diverse species on earth could have come about this way, and doubt that admittedly interesting theories such as those put forth to explain complex systems (e.g., Behe's critics) can explain something like an eye.
As for your question five, try this:
http://www.pitt.edu/utimes/issues/32/000608/12.html
And realize I'm a layman, not a scientist!
I am also a layman, with no formal training in biology beyond the introductory college level. But regarding the question of commkon descent: what formal principal of analysis differentiates between DNA's use in establishing parentage and relatedness among humans, and its use in determining relatedness across species? What general rule can you invoke?
What human experience set outside limits to variation? In 1900, human experience would have set limits to the speed that human transportation could reach, or the altitude that could be reached.
There is a difference between experience as engineering, and experience as a set of principles. What principles are you invoking?