Customize MailChimp Templates

We are using MailChimp to send email to our customers. We want to customize our MailChimp templates for display on mobile devices. Specifically, we want to accomplish the following goals: - modify the template(s) so that fonts are larger (body and some header styles) when email is viewed on a mobile device. - create a "Smart Button" with a hyperlink that: 1. detects if it is on an iOS device (iPhone or iPad) 2. IF on an iOS device, open a custom URL of the form (mycustomscheme://myapp?parameter) 3. IF on a non-iOS platform, open a normal http web URL 4. For BONUS (optional) at Step 2, above, if our custom URL fails to open (because it is not recognized), then open a different, backup URL We believe that this is possible using media queries. We have tried to do this ourselves but could not get it to work. It is out hope that someone who has prior experience with MailChimp can show us how to do this. WRT Step 4 of Smart Button requirements, we do not think this is possible, but if it is, we would like to make this work. A skilled freelancer with the right background and experience with MailChimp will be hired immediately do accomplish these tasks and will be called on in the future, occasionally, when needed to make other changes to new MailChimp templates. In other words, we are looking for a long term contractor who can work with us on this project on and off, as needed, in the months ahead, once this (hopefully small) starter task is completed.