So here's my experience with the challenging Netherlands.
I started with 2 settlers, but space for only one city. With the German and French borders nearby, I couldn't found a city at a reasonable distance from Amsterdam; instead, I sent the settler to Norway. I also sent troops towards Africa to conquer independent Tanja. I'm sure I couldn't have won with only one city, yet only one historical location was available. However, expanding in Norway and Morocco wasn't much of a problem (except that the Norse controlled tiles where I had 77% Dutch culture!), so let's just pretend the Dutch founded their first colonies in Europe...
There are two problems with the Netherlands: lack of space and lack of time. Well, they're not really problems because they're historical and the game is still playable, but they make it a bit less enjoyable. Few cities and no time to train units means a small army, and that means that every somewhat powerful civ will think of you as an easy target rather than a trading partner. Fortunately, I befriended Germany, but France, Spain and Hungary were problematic because they pillaged the Amsterdam area, thus wasting some precious time, and I couldn't do much about it. But! I survived. The large number of techs you start with can be very useful to bribe for peace or to get gold to spend with Const. Monarchy.
Concerning the UHVs: the first one (10 OBs) is very easy; however I was lucky that the World (well... Europe) War started a few turns after and not before 1640, or else I would have miserably failed. The 5 great merchants are not hard, though I thought I would run out of time. To suceed I took Apprenticeship for unlimited merchants and eventually Common law (+100% GP) to accelerate the process.
The third UHV, 4 colonies, was harder because of the time constraint. I was persuaded I would fail because Tanja was not productive enough, and then I discovered that some new tech I got enabled cheaper colonies... So I won with India, Jamaica, Malaya and East Indies around 1793. All the colonies that do not require a Trading Company were quickly built by Spain, mostly, and England. It would seem that the AI does not understand the concept of Trading Companies, since no one built any (fortunately for me). It may be caused by the fact that the projects themselves do not provide any bonus. Perhaps you could add a small benefit to them or try to make the AI aware that the investment will be profitable.
Useful civics were:
Constitutional monarchy to spend the gold surplus;
Bureaucracy to maximize Amsterdam, Common law to spawn GMs;
Apprenticeship for the merchants;
Guilds for the free specialist, and then Merchant Republic because it's so good;
Free religion because I never bothered getting a state religion;
Colonialism for the Trade routes.
Conclusion: the Netherlands are challenging, but winnable. However, they're mildly fun to play, because you always feel time is running away while your mighty neighbours threaten to pillage your small country.
And lastly a screen of the general situation by the end. Because screenshots are fun!