As to your specific questions:
Yes, I usually will read the whole ad, except for occasions that it's HUGE, or if I already know at a glance I won't be making contact. That could be based on pic, rate, or availability.
Yes, I'll scroll down to look at the picture first, but I'll still read the ad. I think posting an ad here without a pic is silly. I'll still look at the ad, but my interest level does drop. Sometimes I'll find her site or 411 or whatever to see pics, sometimes I won't.
I'll look at her site if it's still a maybe. Meaning if I don't already know it's a no. Again, pic, rate and availability.
There are several basic things I would say every ad "should" have. First of all, some personality! Humor is great and goes a long way with me. Or just something sort of smarty pants. It doesn't have to be that, but just show me some personality. An ad that makes me chuckle or makes me think damn I wish I could forward this to soandso, he'd think it's hilarious, will really get my attention. Show me you didn't just paste in your website copy that you hired somebody else to write. Again, every ad should have a pic. I also like an ad to have rates for at least a couple different time options, available dates, as well as whether she's incall or outcall or both. I don't see why any ad couldn't have these things and I get annoyed when they don't.
An ad should also have a link to a personal site or 411 profile or something. This brings up something I never understood. A provider is allowed to put one link in an ad. Why waste it by linking to your reviews here? When I want to see your reviews, it's right at the top of the ad by your name, "see my TER reviews." (I don't mean you literally, I mean the royal you. I don't know if you do that or not.) I understand if a lady is new here so she doesn't have the TER banner on her site yet or her handle isn't linked yet or something like that, but I see many instances of linking to the profile when neither is the case. Maybe it's just me but that seems goofy. I won't say it's wrong or anything because I would definitely be looking at her profile at some point before contacting, and almost always the profile has the links to 411 and personal site, so it doesn't really matter. Just seems like inefficient marketing to have two links on the ad that go to the same place, but what do I know.