According to that text, it should. Break Enchantment does not, however, knock it off. It also won't take off Symbol of Pain which is also obviously an enchantment spell. It may simply be due to the extremely high caster level in Epic, but I've never even seen the attempt to dispel it in my combat log.
No, I keep Holy Aura on at all times in eVoN1, and we still get hit with Crushing Despair. Holy Aura according to that text should also make you immune to Otto's Irresistible Dance, but it doesn't.
In non-epic content, yes. In epic content, their caster level is too high, so they will always bypass your SR.