I bought the tire fire as it was the best bonus for donuts. That said holding out for a deal from gil is prob the best bet. however his "deals" usually cost around 200 donutsso it is up to you.
I logged on as I was typing this and also was rewarded with the 12 free donuts!
Righteousness is gotten by visiting other people's cities and spray painting them. A few of the buildings will have a spray can over them and click on them. Also you will need to make sure to keep your city clean. It randomly goes up and down as well so there is also that but that is the way to do it. Hail Ants signs also increase righteousness I believe. Click on the i icon when looking at things to buy and it will tell you what it improves.