I would like to just print labels off (you can use plain paper to print, right?), weigh them and just drop them off at either the Post Office (they have a drop off slot for FedEx packages) or UPS customer service counter. Are they "free?" Or do I have to pay for monthly services plus postages on top of it? Any input would be appreciated -- thank you!

They are free accounts, fedex you sign up for a personal account with your credit card and then start shipping under your account. The UPS site allows you to fill in the shipping info and then a cc info for each transaction.