What is the goal of Republican tax policy?

I constantly hear Republican politicians calling for more tax cuts, but I never hear them say at what point the tax rate will be the optimal rate for our society or what is the goal for these continued calls for reduced taxes.   I would like to get some feedback as to:

1.  What is the optimal tax rate?  (i.e. at what point does lowering the rate cause more problems than it solves)

2.  What services should the governement perform?

3.  Does the revenue resulting from your response to question 1 pay for the required services in question 2?

FYI, I am a Democrat and I am not trying to disparage Republican tax policy here, I merely want to understand it.    From my point of view,  the current rate for the top tax bracket has been halved since Reagan took office.   How much lower could it go or should it go?    Also the government performs an array of services that I consider vital in modern society:

Protect the country (DOD, Military forces)

Protect the food supply ( FDA)

Ensure safe medications (FDA)

Protect our environment and water supply (EPA)

Ensure the work enviroment is safe (OSHA)

Regulate industry to protect  consumer ( SEC, FTC, FCC, FDIC, FSLIC, CPSC, etc.)

Build Roads, Bridges and other transportation infrastructure( DOT)

Provide income and insurance assistance to the elderly (Social Security, Medicaid)

These are but a few of the many services that government provides.    I would like to get some Republican feedback about what the spending priorities of our government should be.   What would the Republican utopia look like?

Your responses are greatly appreciated.