1) Have you thought about falling back to the advertiser's website if the app isn't installed?
2) Will the link scheme be made available and if so will it be possible to link to apps from within web pages?
2- We've built our own link creator (see footer link on site) to make it easy to learn about other apps' url schemes and create links into their apps. these links can be used from anywhere, including the web. We're adding apps consistently, so let us know if there are any that aren't already there.