Stamp Act: Questions

How does the outrage over the Stamp Act inform the modern debate over the legitimacy of taxation? What's the role of taxation in government?
Had the Stamp Act merely paid for past defense in the Seven Years War/French and Indian War, rather than paid for a new garrison of redcoats, would it have been received better?
Was the Stamp Act a legitimate reason for Revolution or a convenient excuse? Was it both?
Had the tax been for smaller amounts of money, would it have been received better? Or was the problem the mere existence of the tax?
Did the British crown have the authority to tax the colonies? If so, were the colonies wrong to rebel? If not, what kind of authority did the crown have?
The Stamp Act was designed to pay for a new defense force: that is, regular British troops (redcoats) in the colonies. Was this really to fight against Native Americans, or was this an attempt to quell rebellion on the horizon?