1. I know of no study about smaller bees and varroa mite. Beats me whether it helps or not.
2. I keep foundationless for two reasons. I wanted bees but didn't have the money for everything, such as foundation. And partly because I like the idea of bees making the size cell/bees they want. If they naturally make smaller bees, i would think there is a reason for that.
3. All four of the hives are making smaller bees with foundationless. This is year 2 for me, and there has been a lot of new comb built. I believe the original comb built by the first swarm has been shifted into the honey area, and empty frames added to the brood area, and smaller bees have been the result.
4. This small cell comb has all been built this spring during a good flow.
5. For certain there has been some requeening and swarming. The one feral swarm I caught had even smaller bees, so it is possible, but unlikely I feel that it is all due to genetics.
6. Letting the bees build smaller cell size may not be more healthy, but surely it cannot be less healthier.
7. Four hives, and two springs is by no means an exhaustive, scientific study. I just find these small bees fascinating.