While I definitely support Band in A Box to deliver at least some of your requirements, another program that is not a competitor by any means, but may have usable features is SonicFire Pro from SmartSound

It creates royalty free music in very little time, and has many sound library options available including Cinematic scores. It is specifically designed to create customized music for adding to video.

I have many of their libraries, and use them for music soundscapes to go with video.

You don't need to have the video loaded to use it, you can just set the length you want and style details etc, and export the audio for adding to your own NLE if required.

There's a short video presentation available also:

BIAB & RB2025 Win.(Audiophile), Sonar Platinum, Cakewalk by Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M Monitors, Pioneer Active Monitors, AKG K271 Studio H'phones