In answer to the majority of the questions you've posted - Standard C++ has no way of directly interfacing with hardware - such tasks are beyond the scope of the standard. You'll need to visit documentation for your compiler/implementation.

Yes you can create programs for virtually any platform - which is the reason why C++ has no built-in support for any kind of hardware.

Instead of just flooding this forum with a long list of questions, why don't you actually make some kind of an effort to find out?

c++ programs must be run under SOME operating system. You can not run them before an operating system has been booted, unless of course you are writing your own operating system. You could, of couse, install MS-DOS 6.2 operating system on your computer if you want to run true MS-DOS. The console window that you can get with MS-Windows is not true DOS, but an emulated MS-DOS.