The leadership scenario is sometimes inevitable depending on the players you have. It's natural for more experienced players to fall into a leadership role because they have more experience and newer players (or sometimes experienced players who don't want to take charge) aren't comfortable making big decisions and the party lacks direction. Overall it's typically not an issue unless the player starts bossing other PCs around, forcing scenarios that the rest of the party doesn't want, or trying to steal the spotlight.

As for the survival scenario, even if the player describes in perfect detail what they would like to do, you can still make them roll to accomplish it. I allow players to give me an idea of what they want to do, but that doesn't mean their character can do it.

I had a player tell me he wanted to make a chemical compound and he told me exactly what ratios he wanted to put in it. I made him do an intelligence roll because his character didn't have any knowledge: chemistry ranks and he didn't roll high enough.

You can do this for any semi-metagaming scenarios without your players feeling cheated because even someone with ranks in that skill could potentially fail it. You should never let something fly just because the player knows how to do it. You wouldn't let a PC shoot a bow and arrow just because they can do it in real life, so you shouldn't let them perform skills that their character doesn't know.

That being said, you can still allow creative solutions. The water filter is a great example. "You guys need water. What do you do?" "I want to make a water purifier by doing XYZ" "OK, make a survival roll".

It allows your player to be creative and come up with a solution, without letting them metagame.

The leadership scenario is sometimes inevitable depending on the players you have. It's natural for more experienced players to fall into a leadership role because they have more experience and newer players (or sometimes experienced players who don't want to take charge) aren't comfortable making big decisions and the party lacks direction. Overall it's typically not an issue unless the player starts bossing other PCs around, forcing scenarios that the rest of the party doesn't want, or trying to steal the spotlight.

As for the survival scenario, even if the player describes in perfect detail what they would like to do, you can still make them roll to accomplish it (Within reason. An untrained individual wouldn't stand a chance designing a nuclear reactor from scratch). I allow players to give me an idea of what they want to do, but that doesn't mean their character can do it.

I had a player tell me he wanted to make a chemical compound and he told me exactly what ratios he wanted to put in it. I made him do an intelligence roll because his character didn't have any knowledge: chemistry ranks and he didn't roll high enough.

You can do this for any semi-metagaming scenarios without your players feeling cheated because even someone with ranks in that skill could potentially fail it. You should never let something fly just because the player knows how to do it. You wouldn't let a PC shoot a bow and arrow just because they can do it in real life, so you shouldn't let them perform skills that their character doesn't know.

That being said, you can still allow creative solutions. The water filter is a great example. "You guys need water. What do you do?" "I want to make a water purifier by doing XYZ" "OK, make a survival roll".

It allows your player to be creative and come up with a solution, without letting them metagame.