I don't wash my eggs that I keep for my family's use until just before I'm ready to use them. Washing eggs removes the bloom. The bloom is a coating the hen puts on her eggs at the end of the laying process. It seals out dirt and germs.
I also don't wash eggs that I sell and my customers know to wash them before using.
When you wash eggs you should do so in warm water, at least 20 degrees or so hotter than the egg itself. Washing in cold water is a big no-no. Using cold water causes the contents of the egg to contract, pulling dirt and germs into the egg. Warm water causes the contents to expand, pushing dirt and germs up and away from the contents. You should also never soak eggs in water.
Eggs last longer if kept refrigerated. I recall reading an article that said eggs left on the counter for one day age the equivalent of one week in the frig.
I can't really tell you what the local going rate is for a dozen eggs. All my egg customers are either very good neighbors and/or police officers and firefighters that my DH works with, so I sell to them at a discount. It's enough to buy feed for my hens and that's all I care about.
The usual going rate would vary depending on where you live.