The most valuable outcome for your startup would be to identify (or validate) a common and important problem you can solve and to identify prospective early adopters for your solution.
So yes, network with presenters - but if you have a room-full of delegates for a relevant session, many of those could become valuable relationships too. So network with the audience too.
And yes, check out the competition, find out how they are pitching their solutions first-hand and find out all you can about how they price, how they support customers and what are their roadmap intentions. Just keep this in context: you need to know the competitive landscape, but your prime focus is always the end-users.
Another valuable objective would be to research what media and which bloggers are key influencers. You can do this by talking to people, and in the case of speakers it's worth checking out whose talks are best-attended and which speakers get the long queues of people trying to catch them afterwards.
You can also check out what seems to be working for companies trying to engage delegates (those with and without stands). Next year, you'll be one of them. So study how to be one of the best.
And I'd personally resist the urge to talk about your plans. That would be premature - plus there's the danger that you have some great conversations about the whole business of becoming a startup (that you could have at any networking meet), and miss the opportunity to engage with a whole conference full of prospective customers.