Not sure there's much point in those changes to Despotism - Feudal Monarchy is already vastly superior and I don't think anyone would prefer despotism, so a stability penalty would just increase that. The 30% maintenance wouldn't, imo, offset the free units and +1

from barracks. If anything, despotism should be stronger, maybe -50% maintenance cost from number of cities and reduced stability penalty from number of cities, to make it viable for large empires like Byzantium which didn't have feudal systems?
Also not sure about Nobility - I think Bureaucracy is well balanced for smaller civs atm, and focuses on building a strong central city, whereas giving bonuses to specialists and all cities would encourage its use for larger empires.
Agree with the changes to Feudal Law and Organised Religion - the food production in Feudal Law would make it a choice with others, as at the moment it is the best legal civ by some way imo.
Castle Keep, Tower House and Well sound good, maybe reduce the health benefit from hospitals by 1 so the well doesn't increase the overall cap for later civs? Although +1 espionage per population would make the Tower House very OP imo. Maybe save that benefit for a future wonder and just have the Tower House give +1.
Moat will be good if it adds +25% defence which cannot be reduced by bombardment - that would help improve the defence / attack balance, particularly in the face of siege unit spamming. Polygonal Fort then replaces this 25% defence when moats become obsolete.