Someone may try to answer this question you posed, "How can I structure my flow and SharePoint Lists?" But realistically, only you and the people involved in the process will know what will meet their needs. You should first speak to the people involved in the process to determine how the process should be automated, and what data needs to be captured in SharePoint.
As of right now, we have no idea of what type of change request you are automating. Is it a change to a contract, a change to an IT system, a change to a build request, creative copy request, etc.
Once you get the requirements from the users, start building the flow. Then, when you encounter a specific issue, come here to post a question. We cannot really answer questions as open-ended as the one you posted.
For the approvals, you will need to determine the order the approvals need to go to which team, as there is no approval action to do what you have outlined. You will need to send the approval to say finance fist and configure the approval to first to respond. Then send it to everyone in finance who is an approver. If it is approved, do the same thing for the next team that would approve the request until you have seven approvals.
Since approvals must be completed within 28 days or they time out, you will need to consider this within the process. It can get rather complicated if you need more than 28 days for an approval. When you consider this, post more information about your process as it will help for someone to provide clearer guidance.