tips you did, of course - the hat is because of what you have done to the community

just average, it can be for last 24h for example, or for full period of having hat - feel free to propose best way in your opinion

it should show different colours for different ranges of average tip used by the user having hat

(just like SN interface is already able to colour lightning bolt by the article you have donated, i.e. the colour is changing according to the number of satoshis you have donated to the article)

it will incentive generosity on Stacker News for sure :)