1.) Depends how many trips you wanna do :)
The “OneCountryPass” for Netherlands is called the BeNeLux pass and is valid in Belgium/Netherlands and Luxembourg. Not that with a OneCountrypass you can´t use the outbound and inbound journey Means you have to pay to get from your home to the border of the BeNeLux pass validityroom.

2.) Netherlands and Belgium Liege,Gent,Belgian Coast (Küsttram = a tram along the belgian coast), Ostende, Bastogne/Malmedy and ofcourse Brussels :D

3.) What you should see in Netherlands depends on your interrests Nature, Culture, History, major Sights.
Keukenhof is one of the major Sights besides Amsterdam & Den Haag.
Utrecht (Hometown of Eurail & Interrail )
Maastricht
 

Hi Marts!

1. I’m not an interrail expert at all, but i live in the Netherlands, and i can tell you that local public transport is VERY expensive. So i would do everything you can to avoid just buying plain train tickets at the ticket machines in the central train stations. Other than that, I would advise you to visit the following website for all information about trains and other forms of public transport. : https://www.ns.nl/enWhat I DO reccomend is hiring a bike from the institution from this website. Those bikes only cost you 3,45 a day and it’s super convenient for moving around cities and even between cities. You can hand in your bike at every major train station, so you don’t have to bring it back to the place you found it. You will have to buy a personal public transport card, but i would say that’s worth it. More information at https://www.ns.nl/en/door-to-door/ov-fiets
2. You can easily travel to belgium and Germany from the Netherlands. There are local busses that can get you there. Antwerpen is a beautiful city in Belgium you can easily travel to from several train stations/ bus stations in the Netherlands. Also Aachen in Germany is really easy to get to if you’re taking the bus in Maastricht. Even Paris is not that far away ( 3 to 4 hours ) and not that expensive as well. For more information see https://www.nsinternational.com/en/france/train-paris
3. Ask any dutchman, and they will tell you Amsterdam is overrated. Ofcourse it’s beautiful and very vibrant, but it’s also very touristy. That doesn’t have to be a problem, but there are other places you can go to that are as pretty and fun as amsterdam. Haarlem, above and not far from Amsterdam is a cute and old city with beautiful streets. Gouda can be touristy but it has some very old streets and buildings and the vibe is very fun. Utrecht is a bigger city (second or third biggest city is my guess?) But not many tourists. It has cute canals and i think the people and the atmosphere are much nicer than in amsterdam. Other than that: Nijmegen, Den Bosch, and Maastricht are 3 cities outside of the center of the Netherlands, but all very old and beautiful and not many tourists at all. If you’re not big on old beautiful cities but crave a more vibrant setting, Den Haag and mostly Rotterdam are the places to go!! If, for some reason, youre traveling to the north of the Netherlands, the cityGroningen is definetely worth checking out.
   
   Anyway, Thanks for reading this trainwreck And don’t mind the spelling errors!!
   
   Good luck on your travels!