building a performance test suite

Hi List;

I'm preparing to create a test suite of very complex queries that can be
profiled in terms of load and performance. The ultimate goal is to define a
load/performance profile during a run of the old application code base and
then again with changes to the application code base.

I suspect I should look at grabbing these things for load:
# of queries running
# of IDLE connections

and these things for performance
how long the queries run
difference between the runs for # of queries running

What do you'all think? are these valid metrics? should I be looking at others
like pg_statio or pg_stat_all_tables ? If so, what should I look for in these
(or other) tables?

Thanks in advance...

/Kevin