I did an unlock strategy guide of sorts a while back. Might answer some of your questions.
viewtopic.php?f=3&t=2134I should add that some of the details have changed since I made that. The way that banks give money to adventurers changed, making the bank all upside with no downside. Tikki Tooki and Earthmother switched places in unlock order, and the criterion for opening the directional quests are slightly different now. Also, that was when challenges didn't give any money. If I were to do this again, picking off bronze and easy silvers would have been a big part of my planning.