Hi essoteric,
I'll try to give you a hand here. S-corps are "pass-thru" entities for tax purposes, meaning that income/loss of the business is passed thru to the shareholders, who report it on their individual tax returns come April 15.
When it comes to employees, these are murky waters. Some will argue that the owner can just pay himself dividends out of the company, thereby avoiding payroll/self-employment taxes. I can tell you from a practical standpoint that the IRS frowns upon this and will aggressively go after someone who pays themself little or no salary and draws dividends, often re-classifying dividends as salary and then backcharging for employment tax, penalties, etc.
Payroll taxes (social security) are pay-as-you-go taxes, so you need to be sure you have that cash flow to cover your tax liabilities along the way. If you are unsure about this or would rather have a simplified way of operating the business while having pass-thru taxation, you may want to consider an LLC. An LLC gives you the same limited liability protection as an S-corp, while the income is passed thru. The first year you can pay your self-employment tax at April 15. If in any year, you end up owing tax on the LLC's earnings, you will be required to pay "estimated quarterly tax" every year thereafter.
Here's an article that discusses the pros and cons of S-corps vs. LLCs which you may find helpful:
http://www.mynewventure.com./?show=S_Corp_vs_LLC