If you create a project controlled by touch screen it automatically can be played with a mouse. So if yo want to use both touchscreen AND mouse, create a project with touchscreen commands.
Of course there are functions like "right click" and "scroll" that can only be accessible via mouse, so plan your project accordingly.
And about the HD for windows the adapt for cellphones. Even if you create a game in great resolution in HD it will loose quality when you try to adapt it for mobiles because of the scaling of each screen. But yes, it can be adapted.
But the best way of course is for you to develop the entire game focusing in a single platform, and change it later on if you want to reach others. So you will have many versions of the same game for all kinds of platform.