Oh my goodness what a cutie! I don't think I've ever seen a Persian with dilute calico coloring! I've never had a longhaired kitty, so I can't tell you much about caring for her fur, but some general things:
1, 2 & 8. You could certainly try putting something on or next to the butter. Vinegar, lemon, or celery should do the trick. My cat looooves butter too. I put a little bit on a separate plate and put it by her feeding area. I think most of us give a little human food to our kitties, but I wouldn't let your kitty eat where you're eating. That could get annoying for you.
Kitties don't really need treats, especially not cat treats. Most of them have icky ingredients. Freeze-dried chicken or fish are healthy, but they are expensive. My kitty gets butter sometimes, or some roast chicken, the water from a can of tuna packed in water, occasionally a little bit of bacon, as treats.
Wet food is generally healthier for cats than kibble, and feeding a lot of kibble can definitely lead to overweight kitties. People with a lot of kitten experience generally seem to feed kittens wet food 3 or 4 times a day but also leave a little kibble out. When to stop free feeding/cut back on food? Most people seem to do so by 12 months at the latest.
3. I'm not sure why your kitty gets smelly? Is she getting pee or poo stuck to her hindquarters? If so, you might have a groomer give her a trim back there on a regular basis. I don't bathe my cat unless she gets herself dirty, but again, I've never had a longhaired kitty.
4. Some cats just really don't like being brushed. I use a flea comb on mine, and she loves it, but I had another cat who hated it. Some members have said that their cats tolerated a human hair brush, with plastic bristles, but not any kind of cat comb or brush. This might be a situation where treats could be useful...You could also try starting while she's asleep, and alternately petting/combing her. Start with just a few strokes, before she gets upset, and gradually lengthen the amount of time you spend combing her. On my cat who hated the comb, I dampened my hands and stroked her fur. She liked that, and it got off quite a bit of fur, but it won't do anything for the undercoat.
6. I believe there is at least one, but I can't remember the name.
7. If you can, it would definitely be a good thing. I've never done it. I just take my kitties in for dentals when necessary.
I hope others will be by with more suggestions for you!