The Dutch were renowned merchants and conquerors who colonized several continents during the Exploration Age. Like the Spanish and Portuguese, their focus is on naval and gunpowder units. Here goes.
Gunpowder and Naval civilization
Careening/Dry Dock free.
Trade units generate +1 gold en route, rather than after reaching own market.
Receive +50/100/150 (II/III/IV) gold when a new Market is built.
Gunpowder units regenerate +20HP per minute.
Unique Units
Musketeer (60f, 70g) - Hand Cannoneer with high melee armor and 100% accuracy.
Fluyt - Gunpowder ship available in imperial age. Functions like an Organ gun that fires a volley of projectiles.
Unique Buildings
Bourse - upgrade from the Market that fires arrows to protect trade carts. Also generates +30 gold per minute.
Team Bonus:
Markets available in Dark Age.
Unique Techs
III: Stock Exchange 400 f 300g) - Receive +10%. (III)/15% (IV)resource interest for every 500 resources gathered.
IV: Armed Merchants (800w, 650g) - Converts Markets into Bourse, which has longer LoS and fires arrows.
The Dutch civ concept is very early modern. I think Hansa civ would be a better option. The Hanseatic League brought together large Baltic cities that were very important in trade. These cities had a significant German population, which constituted the patrician class and was of the greatest importance in this field of trade and not only. I think such a civ could represent the Dutch as well as Frisians, Pomeranians, Hamburg and other North German nations that were famous for their trade and rich cities.
Thus the Dutch would be represented by both Burgundians and Hansa but on different planes - because the territory of the Netherlands was both in Burgundy and the cities of the Netherlands were members of the Hanseatic League.
I am assuming you mean you receive that percentage of resources you have in the bank. Meaning if you have 1,500 stone you gain 300S per minute utterly broken.
What exactly does this civ offer for any map setting to be actually viable? This civ has no bonus that would actually show up pre-Castle? Nobody is gonna just make 5 markets for some extra gold.
The Flemish/Frisian lands have some good potential for dark age bonuses you arent really exploring. This civ probably needs a more balanced design.
I think that we have more than enough European Civs. There are at least several dozen non-European civs that should be considered before adding in any more European civs.