First, I would suggest being more open. Take some of the concerns you've raised here — feeling useless, not knowing what's expected of you — and go to the CEO with them. Don't be critical or overemphatic. Just tell them the situation you're in and how you're feeling. If they're worth their salt they'll listen and be understanding and try to make things better. If not, at least you’ll know who you're dealing with.
Communicate more frequently. If you’re not sure what to do, ask someone. If they don’t know, ask someone else. You certainly don’t want to bother people every 5 minutes, but if you’re stuck for hours each day that’s not good for anyone.
If possible, get them to tell you the most basic subset of functionality you can build at first. Build that. Take it to them and see what they think. That will probably give them a far better idea of what they want.
Communicate more frequently. If you’re not sure what to do, ask someone. If they don’t know, ask someone else. You certainly don’t want to bother people every 5 minutes, but if you’re stuck for hours each day that’s not good for anyone.
If possible, get them to tell you the most basic subset of functionality you can build at first. Build that. Take it to them and see what they think. That will probably give them a far better idea of what they want.