I remember this coming up before. My appologies!
More honest questions:
But on a related note, are citizens in the US allowed to own fully automatic-firing weapons? If not, what is the rationale between banning them and not other 'scary looking' guns?
They are allowed, but full-auto (so-called "Class III" by the BATF) are many times more expensive (because they must have been manufactured before 1986, IIRC, and because of tax stamps) and require a much more rigorous background check.
ok to change it around a bit, is a handgun much use against a hunting rifle or shot gun at a distance of over 30 feet? Is the only good defense against a rifle another one?
It depends on the skill of the shooter, but in principle yes a pistol shooter's accuracy starts dropping quite a bit at 30 feet, and go beyond 70 or 80 feet and you're probably safe from 3/4 of pistol shooters (just find cover or keep moving). Even at close range, I'd much prefer a shotgun to a pistol, but I can't conceal a shotgun in my vest pocket. But, at 30 feet and up, the tactical options are probably more numerous, unless you're having a shootout in an open field or something.