The design and construction of your solution might well require some of your senior people being available to the software company to help them understand the implications of parts of the tender you sent out. You might well need to resolve some thorny political issues, such as responsibilities for certain things. Ensure that your staff have the experience and authority to resolve these issues quickly, diplomatically, and in the interests of the business.

You should try to ensure you know enough about the development to be sure that there will be no unexpected surprises- it is usually easy to clear up a misunderstanding at the before coding begins. The costs of changes rise markedly as development progresses, so fix it quick!