We are a small company that I am lead developer on, and we have been having on and off meetings with a potential stakeholder for a good opportunity. This stakeholder is helping us directly in getting a proposal together to a group of other stakeholders for software that they have a strong need for. Hopefully if we sell them on our proposal (consisting of very high level features and general deliverables) then they will sponsor the project and it will grow organically from there to users around the country who will see how useful it is.
Problem is that we as a development are terribly bogged down as it is with prior projects, maintenance of existing production systems, and badly needed features on the backlog. As it stands, because this project could be highly lucrative and there are no serious competitors, management wants to act FAST and get the most basic functionality out as quickly as possible, no matter the cost.
This isn't realistic for us without growing our team but that takes too much time. They are thinking about contracting the development work out, but want me to be a business analyst and also have architectural say in the project. When they finish major feature development, they anticipate my team taking responsibility over maintenance so clearly architectural control is important as we want the deliverables to be maintainable.
I am okay with this role, but am unaccustomed to it. In house we typically don't use formalized requirements documents, and instead gather requirements from user stories, use cases, workflows and customer agreements. We are used to formulating user stories but I am afraid that doesn't make sense to deliver user stories to an outside contract company as they will likely have their own project managment who might want to do things their way. I wouldn't want to impose our unfamiliar project managment process on them if they find it alien and it slows them down.
I am thinking that extremely detailed formalized business requirements are in order because we want to be sure that they have the necessary guidelines to create quality software, but I have no idea what kind of effort this will take from myself alone. I am also unsure of when to start. Nothing is official yet, but I have 90% of the information I feel I need from stakeholders. I just don't want to end up with management informing me that the deal was signed, we have to deliver in 6 months and to get him all the requirements documents by the end of the week.
Feeling a little in over my head here, do I formulate user stories or business requirements? Any other helpful suggestions?