Among other things, I build traditional architecture, but oddly enough I live and sleep outside, (have most of my life.) 70 to -40 it don't matter much, so your question about comfort is hard to relate too. I like snakes and creepy crawlies and all things out doors. I love Gerr/Yurt living.
1) I'm wondering if living in a yurt is actually comfortable. I've camped in one and loved it, but that's as far as my experience goes. My yurt would be in the woods in a moderate climate (mild winters, little snow--though I've seen it four feet deep here after a freak blizzard--and fairly hot, somewhat humid summers). I've heard a yurt is harder to cool than it is to heat, but I'm counting on the shade of the forest to help me there.
Your local zoning office can answer you questions, but going through the state will help also and may be better to stay nebulous when seeking answers. I know in most area structures like this are considered "transient" and not taxable.
2) I don't know how to go about finding the codes in my area to see if a membrane-covered, semi-permanent dwelling complies; I'm hoping to avoid digging a septic tank/drain field, and will be using a properly installed & vented composting toilet. Would my pals and I really be able to put this thing up with little construction knowledge? Or should I hire a contractor to help me? How difficult is it to disassemble should I want to move?
Your taste and quality of construction.
3) Would you recommend a new yurt over a used one? Or vice versa?
You can finish them almost like a regular house, it's up to you and your needs.
4) Would a rocket mass heater be a good option for heat? Would I need a back-up alternative heat source? What about water heating? I've considered a combination RMH/outdoor water tank for winter/summer water options.
No slab, not necessary. Deck or raised gravel pad and then your choice of floor.
5) Slab or deck?
I say beautiful and never has been a problem for me...but maybe I am not the best to follow on this, considering what I consider comfortable.
6) Would the wind in the trees be so loud as to make conversation or sleeping difficult? This isn't considered a windy place, but the wind in the trees can be pretty loud at times.
On the structure or the land? So many, and a lot depends on you.
7) What questions SHOULD I be asking?