Your assessment of the republican leadership is correct, your assessment of the tea party caucus is off. It will probably play out the same as the 94 republican revolution, where the leadership takes over the movement and resumes deficit spending.
The goal is not spending or balanced budget per se, the goal is to maximize freedom and minimize the impact of the federal government on the individual citizen. So single payer health care is not optimal if you value freedom of choice. If your only criteria is cost, then we should just make all doctors and nurses slaves, because that is cheap.
Corporations are a construct of government. So yes, if we limit the power of government, corporate power will be limited too.