That looks like a pretty power hungry PC (by carpc standards), I doubt the opus would handle it. Though it might, many people claim they can push the opus well beyond the rated output (whether that's a good idea is another issue).
Whether you can power all your equipment depends on your alternator. The battery really has nothing to do with it, except how long you'll last if the alternator can't put out the required current. I think you're probably okay, but if you want to be sure find the rated output of your alternator and find/estimate the combined draw of all your equipment.
Bass shouldn't affect the HD.