By lodging a provisional and having a released product that implements the invention, I believe no one else can patent that invention, even if you don't proceed with the patent. Ask your lawyer. A patent search will reveal if someone else has patented this already and would be a bit cheaper. Also shop around and get quotes from a couple of lawyers.
Totally agree on the focus issue, my partner is spending all her time stressing about this b/c the clock is ticking and I ended up reading a bunch of patents the other day as well instead of focusing on the product.
Thanks for a business perspective - we are new to this so I really do appreciate your thoughts on the subject.