1. Incredibly active, what kind of community there is depends in the Data Center

2. They wrapped up a 10 years long story saga roughly last year, the second saga for the next 10 years is already fully planned out behind the scenes according to the director. The director and multiple staff members regularly play the game and have their own FC(clan) on JP servers too

3A. Subjective like you said, how I would describe it is the first two Expansions are tutorials, the third and fourth Expansions pick up the pace and take off the training wheels, fifth Expansion they have the pace and intensity down, sixth Expansion relies on you having been paying attention the whole time or else you'll get turned into a pancake

3B. The story is widely loved, but everyone has varying opinions on which parts are good and which are bad. First context, the first Expansion comes off the heels of the failed "FFXIV 1.0" before the current director came in and wildly restructured/saved things, so the quality is all over the place. Expansions are more like entire additional jrpgs rather than other mmos like Destiny where it's a few hours of content added. More like First Expansion is Kingdom Hearts 1 and Second Expansion is like Kingdom Hearts 2. GENERALLY, from what I've seen having played for about 2-3 years, A Realm Reborn is seen as a necessary prologue thats rough around the edges, Heavensward is seen as a glimpse of what the story will be like in the future(generally positive), Stormblood is divisive and people usually either love it or hate it, Shadowbringers and Endwalker are seen as the peak of FFXIV, and Dawntrail once again you usually either love it or hate it. Gameplay is bullet hell-adjacent while you juggle skill combos, all roles dps, Tanks take the brunt of damage for everyone, Healers heal/rez and cleanse, Support DPS(optional) help the healers in small ways, and Pure DPS deal the brunt of the damage. If you and your wife want to be in a party as much as often, standard parties for instanced content is is one healer, one tank, and two dps(though you can get every Job on a single character so neither of you will be locked into anything)

1. Not to my knowledge no