Question about production numbers

I'm assuming each cylinder is 32 km long and 3.2 km in
radius. They rotate once every two minutes and are set up
as ballistically coupled pairs. The initial population of
each colony pair is 500,000 people of diverse racial and
social backgrounds. There are six extrasolar colonies
within 20 light years of Earth, all set up to ensure human
survival when it looks like Earth might be facing a comet
impact. I'm assuming the existence of robotic workers for
space mining and construction, but not for farming and
other relatively safe professions. My story takes place
within the first 70 years after the founding of these
colonies (some of the colonies are very young, some much
older). Some luxuries may be grown for trade, but
generally anything beyond the necessities are not grown.
While I have seen many websites that talk about colonies
raising animals for food, I think that is a luxury that
they don't have. However, I expect they have aquaculture
and hydroponics. I'm assuming technological advancement
in farming practices, but to start out with, I'd like to
come up with labor statistics using our current level of
technology for farming (needs to be sustainable and a
vegetarian - plus fish - diet) and minimal imports and
exports. I know it is hard to guess at what they would
need. My main concern is that I don't so grossly over or
underestimate my numbers that someone reading the story
would balk. Thanks!
-- Felicia