Not going to answer every question systematically, but I've been a big FE fan since it first made its way over to the west. I've played all of the translated games, save Echoes, and played FE6 and part of FE4 with translation patches. I generally play Hard Classic.
I share some of your sentiments in that I'm a little worried about where the series is heading. Awakening had an awesome style and lots of polish but the story and combat felt overly simplistic. I did like the return of the child mechanic, though, and anyone x anyone supports were nice. Maps were pretty
I actually liked Fates a lot from a gameplay perspective. Conquest had some great and varied maps, and other than overpowered royals I liked the unit/class variety and room for lots of strategies. Story was even worse than Awakening's, though, with some one-dimensional and/or underdeveloped characters, silly plot points, and very little consistency.
Personally I'm indifferent to the whole 'Waifu Emblem' thing - and if gameplay in future titles was like Fates, I'd be OK with that - but I'm mostly just worried about the lack of a compelling plot, flat characters, and nonexistent world-building from here on out. Now I'm not saying that PoR/RoD was Shakespeare, but there were some fun politics, sympathetic units, and cool plot secrets all wrapped up in an interesting world. I'd like to see an entry like the Telius games again, but alas, those two sold pretty poorly while Awakening sold like hotcakes. One can hope, though...