Many of your questions (and many more) are answered a tthe excellent
http://www.projectrho.com/rocket/index.html - which basically looks at the physical limitations of engineering (as they are currently understood) and applies them to all the essential aspects of spacecraft design. It's an invaluable read for any aspiring scifi author who hopes to write with a degree of scientific credibility.
There is a section there headed "artificial gravity" that answers your latest question quote neatly, as well as frequent references to power requirements in the propulsion and weaponry sections.