S corps need payroll because the IRS needs to have a way to collect taxes from the business. Because the business is separate from the business owner, they are not responsible for paying Social Security and Medicare taxes on distributions.
The C corporation is the standard (or default) corporation under IRS rules. The S corporation is a corporation that has elected a special tax status with the IRS and therefore has some tax advantages. Both business structures get their names from the parts of the Internal Revenue Code that they are taxed under.
S Corp owners must file Form 1120-S, U.S. Income Tax Return for an S Corporation. Both C and S Corps follow the same guidelines for filing taxes with no income. If you had no income, you must file the corporation income tax return, regardless of whether you had expenses or not.