It is correct that the phone number goes with the SIM card, not the phone. If you buy a different SIM card in different countries, you will have different phone numbers. For example, I bought an unlocked quad band phone from Amazon. Then I got a pay-as-you-go SIM card from T-Mobile. It has its own phone number. When I go to the UK, I will buy a SIM card to use there for lower rates. It will also have a unique phone number that is different from my T-Mobile number, so if someone wants to call me, they will have to call the number that SIM card has. When I switch back to my T-Mobile SIM card, my phone will have the T-Mobile number again. The number goes with the SIM card, not the phone. I hope that makes sense.
You can buy an inexpensive prepaid phone in the Netherlands (phones and plans tend to be cheaper in Europe, especially for international calls). If you have an unlocked GSM phone from the US, you can just buy a SIM card in the Netherlands for your phone. I would suggest buying a SIM card there if you already have a phone rather than ordering one in the US over the internet, as you are likely to get a better deal if you buy in the Netherlands.
If you want to have a phone and a number before you leave, though, you might try Telestial. They have cheaper plans and more options than Mobal. They have phones, but they also give you the option of buying a SIM card only, and you can still purchase a SIM card in the Netherlands and swap it out with the international one you bought in the US from Telestial.
For any of these options, a call or text to someone you want to have the phone number should give them the number so they can call or text you back.
If that explanation didn't help, please feel free to message me.