I would prefer to keep the number of pets to a minimum considering the size of the party (seven players currently), so if you have the option to choose a different ability over an animal companion or familiar, please consider that option carefully. They are not banned, but please be judicious in considering whether your pet is necessary or will be detrimental to another character’s ability to shine in their chosen role.
Multiclassing will use the variant multiclassing rules from Pathfinder Unchained. Classes from the Advanced Class Guide are not eligible for multiclassing as they are already essentially a combination of two other classes. Regular multiclassing rules will not be used with this campaign.