Hey, I do read, but often with a delay!
1. Oracle rolls are for the kind of situation where you just want to "find out" if something could be available or not. A bit like a magic 8-ball. Or quantum world-building. So, yeah, your interpretation of "skill rolls with no risk or variable results" is pretty much close enough. Adding skill in that situation is a bit of a judgement call by the referee. The examples you list - finding a secret or a good sale - if the player gave me a good or funny one-line rationale why their PC's skill would apply this time ... I'd be inclined to either straight up say, "yes" or "yes, if you spend 1d4-1 cash and a quarter of an hour buying some local weirdoes some iguanas-onna-stick."
2. That is absolutely one of the uses of Hero Dice. They're a quick way to regain life (hp). So, the PC can choose - boost your roll now to get a crit? Save your HD for after the fight? Otherwise, life (hp) are one of the attributes that can be recovered after a 1 week rest.