there are pros and cons to tax and accounting...I t's a learning process because every year, policies and rules change. You need to keep updated with the IRS regulations.
Form 941 and 940 are employer federal quaterly tax to report their wages, tips, etc. There are so many taxes that one need to focus on such as unemployment taxes (quaterly), sales tax and withholding tax, coporate tax..etc. It is a headache if you have no patience.
I use Quickbooks Pro2012, it is okay. If its a small business, no need for a CPA but for bigger companies, you will need a CPA.