ForumsStarting a Business

I am trying to set up a non-profit, but am unclear on the steps. We run
an educational meeting that serves up to 600 people per meeting per
year. It has gross annual receipts of about $500K. It requires that we
sign contracts with hotels that puts us at financial risk should the
expected number of individuals not show up. We need to have limited
liability. Whether that should be an LLC or an S-corp it has not yet
been decided ... or whether it is even necessary when starting a
non-profit to form as an LLC or an S-corp.

(1) Can one form a non-profit organization with limited liability without forming an LLC or S-corp?
(1a) If so then how?

(2) If required to form an LLC or S-corp for protection, which is
generally (i.e. ignoring specifics of any individual situation), if
either, best for a non-profit?