How should gaps in management be addressed in a business plan?

Most start-up businesses are going to have some gaps in their overall personnel plan - including management. Don't try to downplay or ignore these issues in your business plan! These are weaknesses that can make or break your business! It is critical that you discuss specific gaps and what steps will be taken to address them. First, list out each position that needs to be fill (i.e. Vice President, Finance Director, etc.). Second, describe the duties and responsibilities that each role entails. Third, talk about when each position needs to be filled. For instance, as certain milestones are reached does that position become more critical? Finally, explain how the positions will be filled. Will you tap in the local job market through the classifieds or a temp agency? Will you rely upon an investor's pool of contacts? Do you have certain candidates in mind, but haven't approached them yet? Your key management functions need to be covered - maybe not immediately in some cases - but you still need to discuss the gaps and the plan to fill them in.

That depends on the strategy being taken.
The SBA will provide guidance for free.