investigate contents of a sqlite3 file
I had a file that was around 30 MB, and issued the vacuum full (not the normal VACUUM as it has the same effect that the Postgres behavior) for reducing its size. After the operation the file got sized 22 MB. I'm pasting the stats of each execution, which shows the differences in between (you will see more failures due to size for the VF).

sqlite&gt; vacuum;
Successful lookaside attempts:       3690
Lookaside failures due to size:      913
Lookaside failures due to OOM:       0

sqlite&gt; vacuum full;
Successful lookaside attempts:       6509
Lookaside failures due to size:      1621
Lookaside failures due to OOM:       0


The command .dbinfo will provide some information as the database page size and its count. Database pages are variable as specified in the file format doc page (this link contains all the internal structures). 

For investigating the contents you can use sqlite_stats1 (the link contains the specifications of this table) table, which will be created after the ANALYZE:

analyze;
select * from sqlite_stat1;