I'll try to answer all the questions in order:
Jacob, energy bill seems to be fairly consistent, maybe a touch higher. As far as I know they used new refrigerant. It was in a pink canister and they took a wrapper of the top.
Tinknocker, on the original repair they did change the drier, but they opened it up once to change the expansion valve and then again when changing the drain pan and they didn't. Would that have anything to do with a strange noise I'm now hearing? I'm hearing a slight crackling or bubbling sound in the air handler. It's not loud, but noticeable. I asked the technician what it was while he was there and he said it was just the freon condensing or expanding.
John, the system has worked for almost 2.5 years with nearly the identical settings, activity, temps, etc..
Doc, I tried to do what you suggested this past weekend. I had the settings at 76 for the entire 3 days. I noticed Sunday and Monday it hovered around 77 -78 until sun down.