Cron

Does running cron use bandwidth?

Not as such.

(technically, you could conceivably use cURL to fetch pages your own website or something similar that would end up using bandwidth, but I don't think this is what you mean)

What are you intending to do in the cron job that would make you think you'd use bandwidth?

Though it generally doesn't use bandwidth, it does use CPU resources. Naturally, if you go overboard with something (such as server CPU load), they'll let you know.

-Scott

I have it run a SQL file, and I would like to run that file every 30 minutes... It is a 1 line SQL statement.

If it's a lightweight SQL file, then there's no worry. That's just a blip on the database server if it's a set of simple SQL commands. And, yes, they do monitor DB servers for heavy loads. Those stats are also available to you in the Panel under Status -> MySQL Usage.

-Scott