Though I am most interested in the answer to the question What process and systems does everyone use to advertise, host, distribute, sell, etc. for their Mac OS X apps?
You ask that almost as if there's a single answer. I don't think there is one single answer that "everyone" uses. I don't think there's one answer that's best, either. It depends on what your app is doing, what kind of hosting you need to support it, what kind of tolerance for non-paying users you have, etc. Since you haven't said what any of those are, it's difficult to advise.
I will be releasing an app shortly. It will have a website hosted on squarespace.com. At least some of the app's remote storage will be hosted on Amazon's S3 service. I may or may not have Amazon DevPay in the first version. I may or may not use Google services (App Engine, etc.) That's the technical side.
On the payment side, I haven't decided yet. I may ship the first version as a limited or trial app, and worry about payments later, if the app goes somewhere. No point investing in a plodding racehorse.
On the publicity side, I will submit it to Apple for inclusion on its Downloads page, via
https://adcweb.apple.com/downloads/. I will also submit it to other channels, which I won't name.
Some of this falls under
Do Your Own Homework. It takes me time & effort to investigate things, and if I learn something useful, it isn't necessarily in my business interests to give that away for free. If you don't know how to find things out by yourself, or expect someone to hand everything to you, or you can't afford to take risks, then you shouldn't be in this kind of business. I'm not saying you are that way, just that it seems this is where the discussion seems to be heading.
A lot of this was learned the old-fashioned way: by doing it wrong and failing. It's painful, but pain is a wonderful teacher. You have to honestly ask yourself (and those who depend on you) what your pain threshold is. If you can't do that, or you don't have a complete answer (with deadlines for ROI, amount of acceptable debt, a fallback plan, etc.), then you probably shouldn't be doing it. I'm not saying you can't be successful at it. Just that if you're not genuinely prepared for any given venture to fail, you could be in for a world of hurt.
Gee, that's a lot more than I intended to type. Oh well. Free advice is often worth exactly what you paid for it.
