Autovac versus manual vac with analyze

I've got about 44GB of data in a few hundred production databases. I'm using PG 8.1.4, but upgrading today (even to the latest 8.1) is not an option. I know, I know. I wish it were, and it's slated here for q2, but I cannot even apply maintenance patches without a full testing cycle.

My auto-vac parameters are:
autovacuum = on # enable autovacuum subprocess?
autovacuum_naptime = 3 # time between autovacuum runs, in secs
autovacuum_vacuum_threshold = 400 # min # of tuple updates before vacuum
autovacuum_analyze_threshold = 200 # min # of tuple updates before analyze
autovacuum_vacuum_scale_factor = 0.2 # fraction of rel size before
autovacuum_analyze_scale_factor = 0.1 # fraction of rel size before
#autovacuum_vacuum_cost_delay = -1 # default vacuum cost delay for
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for autovac

and auto-vacuum is running.

My problem is that each Saturday at midnight, I have to start a vacuumdb -f -z -a or my pg_clog dir never clears out.

The manual vacuum takes quite some time and impacts weekend customers.

So, my questions are:

a) Is the manual vacuum needed for performance reasons, or is auto-vac sufficient?
b) How do my settings look?
c) Is there a way that the clogs get cleared via autovac, would a full vac of just template1/template0 (if that last is possible) do it?