Hi Frank;
I will use your questions to help in the next version of my migration
guide, but you might want to take a look at it anyway.
You can find it at:
http://www.metatrontech.com/wpapers/
It covers many areas of incompatibility between MySQL and PostgreSQL.
My own suggestions is that you wait until 8.1 is released as some of the
issues involved in application porting will be resolved (LEAST and
GREATEST, for example).
Any feedback on the guide would be appreciated.
Best Wishes,
Chris Travers
Metatron Technology Consulting