Disclaimer: I haven't played the Netherlands, though it sounds very fun.
Not sure about ideas. What I'd get: Exploration.
You definitely want to colonize with the Dutch in a standard game (non standard would be creating an European empire). Alternatively you can get Expansion (also allows colonizing) or Diplomatic (strengthen your position on the continent before colonizing).
After the initial diplomatic idea group I'd get one to strengthen my trade. Either Trade or Naval (more ships) or Expansion if you didn't get it first. After that, get whatever you need. I'd get Quality to make my navy even stronger or Innovative for all the nifty bonuses.
I'd expand in the Americas, especially in North America since you can push trade from there towards Antwerp (I need to double check if it doesn't push to WETN; even if it does, you should fight for WETN).
Yes, definitely colonize. You can be a great trading power.
Get fleet basing rights from someone, that should be enough.