Launch the app with the Process class. Wait for it to be idle then get its MainWindowHandle from the Process class. Use this and the window handle of your host window, such as a Panel or whatever control you want, and call
SetParent[
^] to set the parent window of the app you launched to your window.
Be warned, the application WILL show up outside of your application briefly. There is no way around that.
You do NOT have control over the application.
Modifying the window title bar may be possible for some apps but not all and you won't be able to modify everything about the bar. The application you launch has complete control of its own title bar and you will not have ultimately authority over it.
Oh! I almost forgot. Not every application is going to let you change its parent window and some weird rendering may take place.