Very good document. You might consider making this a wiki, So others can add to it?
Well, not really. Anyone who has ever ported a significant application between databases will tell you, the issues you encounter are little to do with SQL syntax, and everything to do with different locking strategies, the query optimizers making different decisions, etc. I worked on one such project recently, it flew on SQL Server and ran like a dog on Oracle 10, until we used query rewriting and stored outlines to…
I totally agree with your points on query optimization, and since you wrote it here, probably no one but me would ever read what you said. On his wiki, more people would read and perhaps refine your statement. As you'd notice, there's already a large incentive for one to go look there to know very specific details of a DB.
The documentation about databases out there are very high level and don't really give very specific details. This page seemed like an excellent start to that.