>Actually, can this be fixed?
>It seems that after a while, shoppers hardly have money to buy
>anything that is not extremely cheap?

Welcome to the economy...if nobody's buying...the shopkeepers don't have any money.

>Another remark: it also resets some after-reboot-only quests.
>So the same question, how easy it would be to change that, so
>those quests will not be dependant on reboots but rather on a
>timer.

No idea which quests you're talking about, so I don't know the answer.