When I looked, the lowest price ad was around $250, with the upper banners running $800 or more per week. Given the click through rates these ads get, that just doesn't make sense for anything but a top tier game, and if you have that type of game you're already getting reviewed there. So you either have to go big/original/polished enough to hopefully garner mainsteam attention from those sites, then hope to god that parlays into a feature from apple, or accept that your app will probably sit in lackluster sales.
As for updates, between 8-10 days is pretty typical, but it seems to be longer on apps with more updates. To be honest, I'm don't think the average app store buyer pays attention to developer names and such. Hell, the average user doesn't do this in big box games either. That's a hardcore dynamic, limited to less than 0.1% of the audience. And often I put some small feature in out of guilt, but I'm probably wasting my time doing so. This is the only thing I've found to affect sales in any major way. I created a lite version of one game, which has pushed my sales up by maybe a few units a week. Getting bumped into the new list is just more effective.
It's unfortunate, because I'd love to really pour time into a single application; but the chances are it won't hit and I feel I'm better off playing a lot of smaller bets than one large one. That might be different if I had a lot more free time to burn though, but I mostly code at night after the kids have gone to bed, and often after coding all day I don't want to work on a long slog, favoring something I can ship in a week or so.
My latest kick is to modularize a large game into a bunch of small apps which can be shipped as their own projects. For instance, right now I'm working on a paint app that will ship as the core of at least two different apps, but will also be a major component of a game I'm working on.
