1) Don't start from scratch; your program may contain components of each of these requirements that could be adjusted so that it would qualify for points towards the seal.
2) Don't reinvent the wheel, there are tons of materials out there that pilot districts have created that you district can adapt to fit your needs.
3) Obviously, trying to implement them all at the same time is a heavy lift. This should be a multi-year roll out that enhances your K-12 Social Studies program over time.
4) Points can be granted retroactively. As long as you have a system or committee in place to determines that a project meets the qualifications of the seal, you can collect student projects and tracking the points towards students' completion of seal requirements.