1, no, I'm not retarded.
2, yes, I've played several, such as pretty much every HALO game, Destiny, Sea of Thieves (more adventure, but whatever), Warframe, Minecraft Hunger Games, Overwatch, and a touch of Fallout (4 and 76).
3, I don't play as often as many other people (I'm assuming like you), and I don't have many gun battles underwater, so less experience here.
4, No, I have only ever done sword + gun (different depending on situation), unlike some try-hards who have no skill with a sword and can't be bothered to put in effort.
5, I play PC, not Xbox; ask details before making assumptive insults you cotton-headed ninnymuggins, or you may risk embarrassing yourself in front of... well no one really- its the internet.