They made it very clear that they did this to prevent people from being harassed while in dungeons.
That's coming later.
You can't change class during battle, or gear. This was a conscious design in the game.
FC's are just guilds. Linkshells are just chat rooms. Friends lists are exactly what they sound like. It'd be really unfeasable to make content that requires you to hit the cap on each of those as it severely limits the communities ability to do these things.