The Kode 94 will be great if you liked the Trance 94. Similar in size, but a better board in every aspect. At your weight, the 86 will be great too. A Flare is quite different. Maybe a bit earlier planing, particularly when not that powered up, but it's a more dedicated spinning/jumping board and not as nice for general riding as the Kode.
About the smaller ones: yes the Q71 will be the perfect one board solution, particularly if you get the extra set of 13cm front fins for the smaller sails. It handles 5.3 fine and is stable and easy with smaller sails too. I think you will extend both the lower and upper range compared with your 04 Acid (a nice board though).
And again yes, the Q66 + Q76 would be perfect for a two board solution. I think you can actually get on the 66 quite early, for sure with 4.7, even if not that powered up. The Q76 will be an amazing light wind wave riding board for 5.3 and light wind 4.7 days.
But while the 76+66 will for sure expand the upper and lower comfort zones a bit, it will not be revolutionary at either end compared to only the 71. Given teh fact that you don't complain much about the high wind range of the A74, I think the Q71 as a single board solutions seems like the most logical choice.
If you're not convinced, just ask again and I can maybe expand on the fine details of light wind difference between Q76/71 and high wind differences between Q66/71.