Are the BYTEA fields stored in the same table as the rest of the data?
yes - and the TOAST tables if it's larger than 1/3 of a page or so. search for TOAST details if you're interested.
Hmm... So a page is 8192 bytes, and it leaves your regular table and goes to TOAST if the BYTEA is more than 2730 bytes. I thought it only went to TOAST when it exceed the page size, not just one-third of its size.