I want to convert a PHP web application which is essentially a series of web forms into firstly a web based mobile first layout/design and then from that create mobile apps. How does Framework7 deal with desktop view, would I need to build a separate desktop version?
It does great with using Material theme which is widely used in desktop apps and website now
Depends on your requirements
And you will probably need to rework your PHP webapp to F7 webapp which communicates with server with API, because anyway you will need it if you will convert it to native app later