Each contractor has its own jobs, gangs, leave and colour.
Untick "Show on week" to keep a field hidden. Hidden fields only show when you click the job card, the same way you edit it.
Every user can edit the planner. Users with "Manage users" can add and remove users. Only Permit can give that right. Anyone can use View only without logging in.
If the planner is published at a new address, paste it above so the copy button gives the right link, and update the SharePoint link too. A new tracker must be a Google Sheet with a tab called Planner Data, headings in row 1, and edit access for the planner owner. The planner data moves into it as soon as you save.