I suspect that's a pretty slow way to try to fill your DB up. You're doing individual INSERTs and possibly in individual transactions (unsure, I don't use PgAdmin); it's not going to be fast.
Try COPYing rows in using psql. I'd do it in batches via shell script loop myself. Alternately, you could use the COPY support of the DB drivers in perl or Python to do it.
this time it doesn't matter - agree COPY is better, this is only one time
3. do Vacuum full to be sure free space is removed VACUUM FULL test.limits;
Which version of Pg are you running? If it's older than 9.0 you're possibly better off using "CLUSTER" instead of "VACUUM FULL".
I am sorry - 9.1.4
Use pg_total_relation_size to include TOAST tables too.
it doesn't metter - conclusion is: table is growing. You are right, for other purposes it should be better to check total size.