@IronicBeauty 1. if you can only use the fire pit to grill fish to begin with does it have to be surrounded by four walls and a roof?
I used the grill rather than a fire pit. You couldn't place a fire pit outdoors without unlocking Astronaut/Space Ranger, right?
(Unless it's within your 8x8 grid? Is that possible?)
Instead, I lived near a grilling area because my founder was going for the Chef career and I didn't want to get stuck with the grill in the kitchen until unlocking Bodybuilder.
Others didn't use Chef for their founder's career.
2. If you can only use the fire pit outdoors then is using a grill indoors the only alternative with a sim that has at least lvl 3 cooking?
No outdoor objects without Space Ranger.
Whether you choose to grill indoors or outdoors depends on how you sequence your careers.
My first (failed attempt), my Chef founder placed a grill in the kitchen. My 2nd (successful) attempt, he grilled outdoors until unlocking the Chef career.
3. Having the Granite Falls vacation pack means you must only grill fish till the culinary restriction is lifted?
Yes, you must catch fish to grill the fish and, initially, you can only have one stack of fish in personal inventory at a time.
4. Is there any restriction on who can unlock a career in the household?
No, only that each sim can only unlock one teen or adult career.
5. Having as many children as possible is ideal in order to unlock as many careers as possible till you max the household limit?
It depends perhaps on what household size you enjoy playing and how quickly you want to finish the challenge.
Initially, have lots of kids is the only option for more career unlocks. Later, you can alternatively do a combination of the following:
*Unlock the Criminal/Oracle career so you can move Wonder Children from the Gallery into your household;
*Unlock Entertainer/Comedian so you can move in more than one sim per generation (in-game NPC or, with Oracle unlocked, a gallery Wonder Child);
*Unlock the Secret Agent/Diamond Agent to be able to move sims out of Apocalypse household.
As I said, other forum members have approached the challenge in other ways, which is part of the fun.