1) There's only one Diamond store in the whole country as far as I know.
2) I live in a huge city that spans across state lines-, it would depend on whether there is enough market and how small am I allowed to go -can you go with say four-five titles a week to get started?
3) with what I have in mind it would take about five or six dedicated customers in the first months to get things running.
4) Tell me about back issues.
5) I would have to make sure to educate the public, hold coherent back issue catalogs, and provide a lot of guidance, and to help the local scene.
6) Also to spend money on advertising.
1) I assume you mean county (if you're talking about Retail Stores with Diamond Accounts). If you mean where the Distributor is, yeah, Diamond consolidated down to a main hub at some point. I'm on the west coast of Canada, and I get my comics from Plattsburg New York. It's a strange way to do it (especially when most of the comics are printed in Quebec - they start in Canada, return to the USA, and then come back to Canada. They're shipped in trucks that cross the Rocky Mountains to get to me. Sometimes in winter the trucks get stuck in snow, and the books arrive, not frozen because they've got no moisture, but very very cold. Where I am it barely ever snows (unlike a lot of Canada, or eastern states), so it's kind of strange to get frozen comics. I digress.
2) It sounds like you have reasonable expectations. That's a good thing - gives you a leg-up on a lot of people who give this a try. There are minimum orders you'll have to meet (I'm not sure what they are ATM, but they're probably a bit bigger than you'd like.) but you can try to keep things as small as possible. (That would be smart). Again, some of the publishers will get you started with credit on their stuff.
3) Juggling pull-files and curating recommended reading lists is an art. You need to understand your customer's taste better than they do. Communication is everything. Get them to tell you what they like, what they don't like, and get a feel for it. Your own taste has to take a back seat. The best way to do that is to learn to love everything, as best you can, for what it is, so that if someone likes it, you can appreciate what they like about it, even if it's not your taste. At the same time, it's important to have good taste, and recommend good stuff. And be honest.
4) I carry one of the biggest back-issue bins in my area. I also have good prices. I don't call a book "near mint" when it's only "fine". I buy back issues from walk-ins at a very honest, very structured system: Comics printed before 1983 and Key issues from after (first appearances and such) I appraise at the price I plan to put on them. I give the seller 1/3 of that. If they want to sell the rest (I don't like to cherry-pick collections and leave people with crap) - I give them 5-25 cents each (usually averages to 10 cents, or $25 a long box) for the rest. I tell them this up front, and I don't "cheat". This actually takes awhile, so people need to drop the collection off and trust that I will call them with my offer in a day or two. All of this is honest and up front. It's the best way to be fair to the seller and to yourself.
5) Yes. I might be a little OCD. Customers always marvel at how organised my store is. I obsessively keep it in order, alphabetical, neumerical, signs, labels, etc. I never understand stores with comics everywhere so no one can find anything. You've got to do the extra work. Owning a store is not sitting around reading comics and chatting with other nerds. (You get to do that, but only when the work is done).
6) I don't know about that. I mean, yeah, get the word out as best you can, at least at first. I stopped spending money on advertising years ago. It never seemed to do anything, and I've seen no difference, but then, I've been there for 27 years. People google "comic store in my area" and they will get my store. That's free. Not much else helps. But you may know more about how advertising works than I do. Just be careful to use it smartly. Everyone will try to sell you advertising that won't work for you. You need to know what will work.
Another note I'll give you is, location is everything. Look for a place that has the right ratio of visibility (and accessibility - parking, transit, etc) with as cheap a lease as you can find. This is not easy, and very important. There's a reason that a lot of comic stores are (let's say) rustic. Just don't be dirty. There's a mom-and-pop charm to a worn-down building, but obviously don't get a dump. I don't know how malls are where you are, but where I am, they are dying and they're very expensive. I would avoid them, in spite of the foot-traffic, unless you know one that's still bustling and low-rent, but I can't imagine that being the case.
EDIT: Oh, and carry Magic Cards and D&D books. They take up very little space for their $.