Is there a way for me to confirm that it is a silver maple? I keep looking at leaves, but due to the discloration, it is really hard for me to confirm. The leaves on the small branches that I can reach are also much smaller then ones on higher more established limbs.

Assuming it is a silver maple, if I cut it down can that be done any time of the year? Once cut down, can I replant a different tree in close proximity?

leaves
http://images.google.com/images?q=silver+maple+leaf&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&ei=MGfvSoiHL87FlAfhovn_BA&sa=X&oi=image_result_group&ct=title&resnum=1&ved=0CCQQsAQwAA

Bark
http://images.google.com/imgres?imgurl=http://images.absoluteastronomy.com/images/encyclopediaimages/s/si/silver-maple-bark.jpg&imgrefurl=http://www.absoluteastronomy.com/topics/Silver_Maple&usg=__ycpWlP522EPZ2TfGGBp9OoKcga4=&h=135&w=180&sz=17&hl=en&start=16&sig2=Ian-FuPlnN7HkluHbDhkiw&um=1&tbnid=jr3DPrVyaAiR-M:&tbnh=76&tbnw=101&prev=/images%3Fq%3Dsilver%2Bmaple%2Bbark%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26hs%3DuX6%26sa%3DX%26um%3D1&ei=VWfvSuPJBZ20NO-UmOgP

when you say cutting it down, cutting it as you mean prunning, or cutting it and turning it to firewood?
I assume the latter, i don't see why not - then why would you care if its a silver maple? , but check with your local building or parks department, especially since you might need to close the street for a bit.

You also might get shoots in the spring off the trunk, just trim them off, once it uses up all its reserves, it'll be gone.

as for planting a new tree, you might want to get rid of as much of the stump and roots as possible, since it might block new root growth of the new tree.