Here is what the plan should be for Homecoming Development
Refactor the code using modern standards and techniques and include lots of comments if they do not exist. This not only makes the code more stable, it is required if you are going to have a significant number of people working on it.
Add automated testing to the code as much as possible so that testing is fast and reliable.
Create tools so that as little of the game content is code as possible. Where this requires re-writing the code to support the tools - do it.
Costumes
Missions
Zone changes (changing tree leaf color, changing buildings, etc)
Adding/modifying villain types in existing groups and adding new villain groups
Modifying existing powers
Adding new powersets and ATs
As each toolset is created, create a subgroup dedicated to that content. So once you have good tools for adding and testing costumes without requiring devs, create a costume group for costume pieces.
Determine what the limits are for costume pieces. Can we have unlimited pieces, or is there a limit due to memory, processing, etc. If there is a limit, create a costume philosophy - generic pieces for more re-use, match NPC costume pieces to fit into the world, specific cool pieces for the coolness factor, etc. Then have a group that creates costume pieces, accepts work from others, reviews and modifies them as needed, approves them, and adds them to the game.
Determine what the limits are for missions. Can we have unlimited pieces, or is there a limit due to memory, processing, etc. Come up with a mission philosophy - following canon, are custom villains allowed, use of AVs, etc. Decide if you want to revise the old missions, just add new missions, or remove old missions that are considered too bland or painful (looking at you patrol missions).
Zone changes, etc..