1. while true, PG has other features (e.g. partial indexes) which can make a big difference as well. Completely depends on the scenario. Sometime mysql will 'win', sometimes PG. No real reason to pick one over the other, unless you know that in your situation a particular feature is a real must-have.

2. use a connection pooler (e.g. pgbouncer), problem solved, good practice anyway, even with mysql

3. what (practical) edge do you see given the replication features in 9.1?