As far as selling, you'll need to look at your situation both ways. If you sell to a large company, you can typically expect one big payout with nothing long-term. If you go on your own, you have the advantage of long-term income and profits--with the added incentive of a "sellout" on the back end at some point down the road.
Play both sides--and you'll be in a better position to determine what will work best for you.
All the best.