How to VACUUM this table? "998994633 estimated total rows"

Hi,

I'm just curious about a VACUUM plan of this table:

1st) When to do VAUUM?
2nd) How often to do VACUUM?
3rd) With which postgresql.conf paremeters to set up vacuum?
4th) When to do a VACUUM FULL?
5th) Can autovacuum of 8.1 be used in this case?

I'm a little bit afraid about the size of the table, but I think
somebody should have a solution...

Here is the complete ANALYZE output of the table:

INFO:  "tbl1": scanned 300 of 27744713 pages, containing 10802 live rows
and 0 dead rows; 300 rows in sample, 998994633 estimated total rows

The size of the data is 340 GB, this are 40% of the disk-array.

Thanks is advance.

Marco