SQL & Binary Data Questions

Hi,

I see people use postgreSQL for storing their binary data including
images, etc. Here are a few questions I would very much like to have
expert opinions on:

- Is it not faster / more efficient to store binary data using file
system and let DB keep the path?
- I know of only one way to interact with PostgreSQL and that is using
SQL. Since it has powerful bytea support, I'd to utilize it by storing
my sterilized data structure into the DB. Is this practice recommended
or discouraged? Is there any better method of pushing binary data to
postgres besides parsing it into ascii sql which seems extremely
inefficient to me.
- Does it make my queries any slower if the rows are bundled with
binary data (that has nothing to do with the query)?

I am using python as my backend, and I am programming a web application
for which speed matters.

Thank you,
Sia