For example the French nobility before the revolution. Would they have their own fortune that they would use for paying their servants, food etc., or did they have access to the entire nations treasury? And how did that compare to other kingdoms of the era (Russia, Habsburg holdings etc.). How did it change after the revolutions in countries that retained proper monarchies, like German states/Germany and Austro-Hungary?
I think you're overestimating the degree to which central economies existed in Early Modern Europe. Nobility in France goes through a few different phases, notably the uptick in nobles of the robe, but if we're looking at the nobles of the sword--essentially the old school, landed nobility--then not only did they have their own money, but often times the king would need to borrow from them, giving the nobles an opportunity to extract concessions. Especially before the efforts of Louis XIV, power and wealth in France was pretty decentralized. The idea of a nation state (which would be a first step towards a nation's treasury) didn't exist. The German states are even more scattered (and their coinage is a nightmare for historians to keep straight) since pre-Frederick, there wasn't really a central authority figure for the Protestant states. Someone once described them as "political confetti," which is pretty apt.