These were specifically addressed in the appeals decision. The appellate court decided that the judge erred in restricting the testimony of Ward. Strictly speaking, the appellate court did not disagree with the definition of "forensic expert", they disagreed with the way the judge defined "forensic expert" (a slight but important difference) and the subsequent decisions to restrict Ward's testimony. They also disagreed with the judge not allowing Massuci to testify, which proves the last sentence incorrect.
That's correct, no pre-existing motive to kill Nancy in particular. Except to keep her from identifying her abductor(s).
You are a local, which means that you've probably traveled the roads of Cary around Lochmere. Many are very isolated, particularly on a Saturday morning. There are tons of trees, most houses are in developments, lots of places that are out of earshot of people. If someone was targeting a runner, they would certainly not do it in a place where they would likely be heard. And I will also note, one of the witnesses did see something suspicious with a van on the road near a runner who they thought was Nancy. That witness may not be reliable, as memories never are, but it certainly it discounts the "why did no one see anything" argument.
