> some elaborations on things they should / shouldn't do when writing code

Hm-m-m... Not sure whether I get you right, but your hint give me the following idea:

after submitting an answer, if it is correct, the user should be able to view some editorial remarks at the results page - discussing good and bad approaches to the problem.

For example some people here used each-by-each comparison (with O(N^2) performance) to filter out non-unique words in a string instead of hashmap...

Thanks, this looks like important feature I should add!