How much is a Representative and/or Senator paid?
Both US Representatives and US Senators receive a base salary of $174,000 plus benefits. The Speaker of the House receives $223,500, and the President pro tem of the Senate and majority and minority leaders in both houses receive $193,400.
How does that compare to the average executive or business owner in the US?
I don't know of any way to calculate 'average business owner'. This is too broad of a definition and fraught with other complexities (such as does the owner even draw a salary?). Plus, I'm not sure if there is a strong correlation between a business owner and a member of congress.
Some possible stats that might work for comparison:
What is the average Net Worth of a member of Congress vs. the average net worth of a college educated American?
The median net worth of a member of congress: $1,008,767
The median net worth of a college graduate (household) in the US: $195,200*
* Note that this stat is kind of hard to find. That number is from page 17 of the referenced PDF report. Also note that that is a household number where the head is a college grad.
What proportion of members of Congress are millionaires or billionaires?
Per the aforementioned article referencing the median net worth of a member of congress, 52% have a net worth over 1 million dollars.
I believe that the percentage of billionaires in congress is 0%. As of 2010, Darrell Issa was the wealthiest in congress with a net worth of only 700 million.