Prices do not usually change a lot during the day but may change from day-to-day. A few days ago the price jumped 5 cents per gallon (3.8 liters). I am guessing that location has a lot to do with price. If the location is bad, you need a good price to attract new customers.

Sometimes a gas station lowers prices to attract new customers, and once those customers start to like that particular gas station then they can raise compared to other stations and people do not care much anymore.

You had some great questions. Sorry that I do not know better answers.