In case you haven't realized it, you are being offered two conflicting schools of thought on frame spacing.
1. Put 9 frames in a 10 frame box to improve ventilation and allow the bees to draw the cells out more, which may produce larger/longer bees.
2. Put 11 narrow frames in a 10 frame box (or 9 frames in an 8 frame box), with either small-cell foundation or no foundation. This will produce smaller bees, which some beekeepers believe provides an advantage against mites.
I recommend sticking with standard frame spacing (10 frames in a 10-frame box or 8 in an 8-frame) to start with, unless you can find a good mentor who uses an alternative setup.
For whatever reason, beekeeping is less standardized than most modern agriculture, and it is quite common to see experienced, successful beekeepers practicing and promoting contradictory methods. Some of this has to do with regional differences, so I would encourage you to pay most attention to advice from nearby beekeepers, and to visit 3-5 bee yards in your area to see how the locals do things.
The treatment-free crowd is especially full of ideological differences, which arise as follows:
Beekeeper A is determined to be treatment-free, and experiments with a wide range of practices, hive designs, etc. Eventually she succeeds in reliably keeping bees on small-cell foundation in top bar hives, and quite logically concludes that this has something to do with survival. So she promotes this as a way to be treatment-free. Beekeeper B is also determined to be treatment free, but finds that his best survival occurs in triple-deep Langstroth hives with moisture quilts, so he promotes these changes as the best solutions. Both may be "correct", in a sense, in that both have developed bees that do well in a particular hive configuration and might not do as well in an alternative design.
I would encourage you not to commit to treatment-free in your first year or two. Maybe avoid chemicals that leave residues in wax, but be open to using the "standard" nosema (fumagilin) and mite (thymol, formic acid) treatments. I say this as a beekeeper who lost both of his hives in the first year. Going treatment-free means accepting higher losses for a few years, and if you have two hives "higher losses" may well mean you have no bees in spring. It's kind of like learning to swim. First you learn to float, then paddle, then eventually the butterfly. But if you tried to learn the butterfly first, you would struggle and probably sink, and you might give up on swimming as too hard.
To add to my earlier comments, Langstroth hives allow you to harvest honey without destroying the comb, but only if you have access to a honey extractor. If you aren't planning to buy an extractor, you will need to crush and strain, in which case the Langstroth advantage is less apparent.
Mark