Hello,
I am software engineer for a company in Romania, and in my spare time I work as a freelancer with my partner. Together we have over 2 years of experience in iOS and OS X development. Please check my portfolio for an overview of the apps we worked on.
Unfortunately, we only develop for iOS. Since you didn't specify that you need both iOS and Android developers, I will post this bid.
Because the link of the iOS app does not work, I can't give an opinion or an estimation for the request to check the currently available features (ensure both apps are free for download, ensure all links work properly and are pointing to proper URLs, etc). What I can say though, is that we can check the app setup page in the iTunesConnect website. Here are all your contact details and all the settings for the app (like pricing for example). Since we uploaded more than 50 apps on app store (I rebranded the Launchpad app in my portfolio for many schools), we have experience with the iTunesConnect platform.
Secondly, regarding the features that need to be coded, they are standard and will not raise any problems. We still need some clarifications (for the "push to call" feature for example), but I will not discuss them here. For the last request, the one in which you said you needed to allow customers to view your latest sale email, I propose using a Parse database, in which you will store the email and the app will take it from there.
Let me know if you are interested in working with us.