Don't apologize! We're happy to have you here,and I say welcome!
Only that a fossil is, well, only a fossil. It proves nothing beyond the fact that it existed at a point in time. How long ago, under what conditions it fossilized, how it relates to other fossils is not evident.
Your correspondent obviously hasn't read much about fossils. Yeah, it might not be evident to a layman with no real interest in some fossil how it got there or how old it was, but these items are of very great interest indeed to the palaeontologists who carefully dig fossils up. Any paper on fossils that you see in
Nature or
Science or
PNAS will spend quite a bit of ink (or pixels, maybe) on exactly all of those issues.
Tiktaalik is a wonderful example a fossil for which all three of the items your creationist mentions are addressed in detail in the paper announcing the discovery.
Nature 440, 764 - 771 (06 Apr 2006) - and I can email you the pdf if you want. See my profile for my address.
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