1) Auto-vacuum configuration:
=============================================================================================================================================================================
 autovacuum                      | on                                           | Starts the autovacuum subprocess.
 autovacuum_analyze_scale_factor | 0.1                                          | Number of tuple inserts, updates or deletes prior to analyze as a fraction of reltuples.
 autovacuum_analyze_threshold    | 50                                           | Minimum number of tuple inserts, updates or deletes prior to analyze.
 autovacuum_freeze_max_age       | 200000000                                    | Age at which to autovacuum a table to prevent transaction ID wraparound.
 autovacuum_max_workers          | 3                                            | Sets the maximum number of simultaneously running autovacuum worker processes.
 autovacuum_naptime              | 1min                                         | Time to sleep between autovacuum runs.
 autovacuum_vacuum_cost_delay    | 20ms                                         | Vacuum cost delay in milliseconds, for autovacuum.
 autovacuum_vacuum_cost_limit    | -1                                           | Vacuum cost amount available before napping, for autovacuum.
 autovacuum_vacuum_scale_factor  | 0.2                                          | Number of tuple updates or deletes prior to vacuum as a fraction of reltuples.
 autovacuum_vacuum_threshold     | 50                                           | Minimum number of tuple updates or deletes prior to vacuum.
 log_autovacuum_min_duration     | -1                                           | Sets the minimum execution time above which autovacuum actions will be logged.
=============================================================================================================================================================================

2) Auto-vacuum daemon is running:
ps -eg | grep autovacuum
5432      6504  6001  0 Apr14 ?        00:02:45 postgres: autovacuum launcher process    

3) Table sizes:
SELECT nspname || '.' || relname AS "relation",
    pg_size_pretty(pg_total_relation_size(C.oid)) AS "total_size",
    pg_size_pretty(pg_total_relation_size(C.oid) - pg_relation_size(C.oid)) as "External Size"
  FROM pg_class C
  LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
  WHERE nspname NOT IN ('pg_catalog', 'information_schema')
    AND C.relkind <> 'i'
    AND nspname !~ '^pg_toast'
  ORDER BY pg_total_relation_size(C.oid) DESC
  LIMIT 20;

     relation     | total_size | External Size 
------------------+------------+---------------
 public.abcd      | 1108 MB    | 592 kB
 public.xyz       | 5904 kB    | 56 kB

4) Last run auto-vacuum:
SELECT now(), schemaname, relname, last_vacuum, last_autovacuum, vacuum_count, autovacuum_count FROM pg_stat_user_tables;

              now              | schemaname |    relname    | last_vacuum |        last_autovacuum        | vacuum_count | autovacuum_count 
-------------------------------+------------+---------------+-------------+-------------------------------+--------------+------------------
 2015-06-10 01:03:03.574212+02 | public     | abcd          |             | 2015-04-18 00:52:35.008874+02 |            0 |                2
 2015-06-10 01:03:03.574212+02 | public     | xyz           |             | 2015-05-02 06:01:35.220651+02 |            0 |               20

NOTE: I changed the relname for above two tables due to confidentiality.