There are some 3rd party programs for wrapping html, css, js into a standalone app for mobiles such as phonegap, appcelerator, and others...
As far as a browser page vs standalone app, it depends on the functionality you're looking for. If you want access to the device information like gps, camera, etc you want a standalone app, if it's just showing a different version of the company website a mobile site should be fine.
If you don't use a "framework" you will have to write 2 versions of the app in java and objective c for native deployment on both platforms.
I make mobile games as standalone apps using a game engine called Unity 3d and it's awesome, but with the basic version there is a watermark on the app. But it allows you to write all your code in C# or jscript and it takes care of porting it to android and ios native formats, or to a web browser build.