1. Since a number of components install as needed, you will not be able to fully use the program on a computer that is not attached to the internet. However, this will not affect the trial, because:
2. The 30-day trial does not include components that install as needed, so you will not get the full set of templates or the ability to edit AVCHD and other high-def files natively. Also any video you render will have the Adobe watermark across it.
3. Yes, yhou can mix music and video of any lengths.
can it add music to different length avi movies?
or do i have to provide the music
With SmartSound, there is a minimal music library installed, and it is accessible, when you install SmartSound Sonic Fire Pro.
Beyond that, there are maybe 1000 songs, that one can buy, either one at a time, or via the SmartSound Libraries, on disc.
Or, as I said, you can add any music to any video (assuming it's not copy protected, as iTunes often are).