1- Can I use QNX as one and only operative system, without installing on the hard disk a version of Linux or Windows?
2- Are the interface of QNX and the interface of Windows very different?
3- With QNX, can I use software as Photoshop, Flash, Swish, Dreamweawer, Corel Draw?
4- If I want to reinstall Windows, what’s the procedure to format QNX?
yes, of course. Or you can install things so you have QNX and additional operating systems.
Fundamentaly? No. In details? yes.
No, you can’t run Windows software on QNX.
Just delete the partition when you go to install windows.
You might want to look into something like Partiton Magic to resize your windows partition and install QNX into the newly freed space. Then you can have both at the same time.