Campaign weapon unlocks

Just got the game. Snooping around on battlelog and noticed a few weapons you can unlock by story mode. Are these early into the story mode or have to finish the whole thing? Does it matter the difficulty setting? I see P90,M249,REX are to name a few
unlocks. I hear that story mode some times deletes it self? Data corrupted? If and when that happens do we lose the weapon unlocks? I'd hate to waste my time on story mode then game gets corrupted and lose like 4 hours or whatever for a unlock that has
to be re-done again. I wouldn't mind that P90 or M249 though.

:)

 

Cleaver Execution

You can do it in campaign without having to unlock it. All executions are unlocked in campaign. Any other gametype requires you to unlock the weapon ex by getting so many kills. Just find a cleaver, down a guy with the lancer, pistol, ect, and hold Y with
the cleaver equipped.

 

Finishing moves, Execution moves achievement

You can just look it up on the Stats in the menu. You can just play campaign and get a weapon and press Y and it will do it. You don't have to unlock it in campaign.

 

Your achievements and unlockable contents from the campain are saved on the cloud. You will not lost your content