These last couple of posts have dramatically reduced my enthusiasm for Starfinder. I was really looking forward to a universally compatible game that would allow me to introduce more Sci-Fi elements to my Pathfinder games (and vice versa). Making changes to things as fundamental as armor class, hit points, and iterative attacks means that I can't just hand my players books from both systems and say "go to town".
Another thing to consider with regard to multiple familiars is classes or class features which require a familiar of a specific kind. For example, a Druid with the Eagle Domain gains a Hawk familiar ("You gain a hawk familiar. Your effective wizard level for this ability is equal to your druid level. Your druid level stacks with levels from other classes that grant familiars when determining the powers of your familiar"), while a Bard with the Sea Singer archetype gains a familiar that must be a Parrot or Monkey ("At 2nd level, a sea singer acquires an exotic pet—a monkey or parrot (treat as raven)—that gains abilities as a wizard’s familiar, using the sea singer’s bard level as his wizard level.")
By the "you may only have one familiar" interpretation of the rules, what happens when an Eagle Domain Druid multi-classes as a Sea Singer Bard?
Or, since Clerics may take Animal and Terrain Domains, what happens when a Cleric takes both the Eagle (Hawk familiar) and Serpent (Viper familiar) domains at 1st level? Clearly said Cleric is able to have more than one Familiar.
Thus characters must be able to have more than one familiar...
So it stands to reason that ojamojallo reading of the rules is correct. If a class grants a familiar, you gain a new familiar AND your levels in the relevant classes stack for determining their abilities.
On the subject of food, I got a hold of Cooking With Class and was somewhat disappointed of about the lack of food to make with Craft: (Cooking). I liked the product but one of the things I was looking forward to were food that were stat relevant or feats to make food stat relevant, like bonuses to diplomacy towards people who eat your cooking based on your Craft: (cooking) check and so on.
Any products that can give me that?
I doubt you'll find a single source for all your cooking-in-D&D needs. There are lots of little references to cooking and eating. Monte Cook's Arcana Evolved introduced a 0th-level spell called Enchanting Flavor that granted a bonus on Diplomacy checks if people liked your cooking--but no other cooking-related abilities.
The situation you describe is the sort of thing that seems simple enough that you should just house-rule it (or talk your DM into making a house rule). A lot of games I've played in or run tend to err on the side of "Wow, that's an impressively high check you made in X skill, the high muckity-muck is so impressed that I'll give you a +X bonus on your reaction/diplomacy/charisma check". Good rule of thumb for that kind of thing is just having a high Craft/Profession check act as "assisting" yourself on the following Diplo check (maybe DC 20 for the self-assist instead of the normal DC 10 to aid another).
One of the guys in my group has written a class called the Gourmand. Makes cooking completely relevant for Pathfinder campaign. I'll have to check with him to see if he has a copy of the class I can post.
The game in question has rotating GMs, so a lot of idea cross-pollination has happened. One has been that extremely high Cooking checks using magical ingredients (i.e. dump a potion of haste into a pot of soup) can result in magical effects for those eating it. These have all been based strictly on skill checks and not officially tied to any specific class, feats, or class abilities.
I'll see if I can compile the various notes people have made on such effects and come up with some kind of unified rules for that which can be shared--so far its all been DM rulings and off-the-cuff rules-making.