i thought these were pretty good questions. i should like to point out something else re point 3. certainly no one would expect a complete fossil record, for the number of fossils of everything ever living would not fit comfortably on the entire earth's surface! however, a more relevant issue is whether we have a representative fossil record--whether we have a fairly random and distributed sampling of organisms from different time periods and locations or whether it is instead bunched up. if it was the former, we could naturally draw better conclusions from the record. if it was the latter, which evidence indicates it is, then the record has natural gaps introduced into it and makes a paleontologists work more difficult. certain areas at certain eras under certain climates are more conducive to fossilization than others and we therefore have a very spotty record, even with the little we have. for example, there is almost no hominid fossil record in africa during a window of 1.5 million to .5 million years ago, but plenty from earlier. its unfortunate, but it can only improve over time. the last 15 years alone have seen a mushrooming in the availability of fossils to the world.
mox
(edit - added decimal points in dates - big difference)