Seeking 401k Advice With International Component

Hello all,

I'm soon to be 37, and for much of my professional life I haven't paid much mind to my 401k/pension accounts across my employers. With a daughter now, I'm looking to finally get my shit in order. The trouble is, I'm unsure where to begin or what best moves to make.

I've had three jobs in the US and currently have one in the Netherlands. My past US 401k accounts are all separate places (one in Alerus, one recently migrated to Vestwell), and my current pension scheme is managed by BeFrank. We're still on the fence about calling the Netherlands our forever home, and if it isn't it's likely we'll move back to the US.

I'd appreciate any general advice or links that'd push me to be more knowledgeable about my situation. And if the best answer here is "wrong subreddit, post here instead" then perfect.

A few specific questions I have:

• Should I be rolling the separate 401k accounts into one, or is leaving them separate fine?
• Is there any expiration on past employers managing your retirement accounts? I mean I'm sure if they go out of business things will change, but I still get emails occasionally even years after employment about my accounts from their HR.
• Should I keep the accounts in their separate countries? I'm completely in the dark on what moving a retirement plan from the US to the Netherlands would entail, or vice versa, but I'd wager there's at least some tax implication right?
• Is there a registry or other way to look up existing retirement accounts across other platforms? I'm almost certain one of my previous employers had included some sort of retirement contribution in their benefits, but at least in my digital records I can't find any mention.

Any help big or small with any of this would be greatly appreciated, thanks!