"Why would Saddam send his supposedly existing WMD's to Syria?"

I think you have to understand that Saddam placed a lot of emphasis covert operations (see history regarding to Stalin). It's possible that Saddam had groups operating in Syria. If Saddam put WMD in Syria it wouldn't neccessarily mean that the Goverment of Syria wanted them there. One way to understand Saddam is don't think of the world as having borders- it well known that he had a significant smuggling operation- a large portion of National income came from smuggling. Syria as a chunk of land has advantages- the US can't legally operate in Syria [so it's a barrier to the US but not to Saddam].
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"The US will get all the contracts to rebuild Iraq, the argument being that it sent its soldiers who risked their lives. Good, but then, why is Blair in favor of a UN involvement in that?
Didn't the UK also send soldiers there?"

Bush and Blair have the same position in regards to UN involvement.

"If the US wants to dominate part of the world, it's going to cost a lot! At the cost of a manned Mars space program, too."

Well, first you have to understand that the US does dominate the world- that's what is meant by the term Superpower. Next, you have to understand that the US doesn't *want* to miltarily dominate the world, or not even economically dominate the world. What the US wants is friendly govts which have free trade which are at peace. Therefore as a general rule, the US prefers that all countries are democrat and that these countries make decisions which are in the interest of it's citizens.
And as far as Mars. I think it's obvious that if the Moon has minable water, that we should first focus on exploring then exploiting this resource- this will enable us to move towards colonizing Mars.