Germany/Netherlands

going to a small town in the Netherlands for work in early Sept but I'm staying in Düsseldorf.

Are you commuting ever day from Düsseldorf to your small town? Sounds like a long journey, can't you stay in your small town.

10 - 4 = 6 days to yourself. Where are you flying into and out of? That affects your choice. Suggestions: Amsterdam (worth at least 3-4 days), Cologne, Gent, Brugge. The Rhine Gorge south of Cologne, from Koblenz to Bingen.

No to a rail pass. If you choose train travel, which is the best option if you are visiting cities, just buy normal tickets. Advance purchase gives big discounts.
If you choose to tour rural areas, then car.

Working in Neterveert. Flying in and out of Düsseldorf. Should I stay in The heart of Amsterdam or outskirts

Google hasn't heard of Neterveert. The nearest approximation is Nederweert, but that's in the bottom right corner of the Netherlands, nowhere near Amsterdam.
Düsseldorf seams a strange airport to choose. Most of the Netherlands is nearer Amsterdam (Schiphol) airport, which has many more flights than Düsseldorf.

For your 6 days, do you want cities or countryside?

It is Nederveert. Spell check screwed up. I'm open for my 6 days. I enjoy drinking, eating , some churches, countryside . I'm more off the beaten path type person

Touring churches, some museums

Weert is your closest centre for train connections to Amsterdam.

With 6 nights at your disposal ...
Day
1. Weert to Amsterdam (3)
2. Amsterdam
3. Amsterdam
4. Via stop in Cologne to Koblenz (3)
5. Day on the Rhine
6. Day trip up the Mosel to Trier
7. Direct hourly trains (1hr 52min) to Düsseldorf Airport

If you will be traveling to distant cities, like Berlin, Dresden and/or Munich, a German Rail pass might in fact be a very good idea. It depends on where you intend to go.

Normal train tickets would cost you €120 - €140 for each of the 3 legs of a D'dorf - Berlin - Munich - D'dorf travel triangle. If you're under 28, a 3-day German Rail pass is only €157 total (so about half the price of normal.) You'd pay €198 if you're 28+ - still a lot less than normal.

Advance-purchase saver fares will offer some savings over the normal price - but they also lock-in the trains you must use. And at this point, only several days before you leave, they are very unlikely to save you very much money. Tickets for your travel dates have already been on sale for nearly six months - so the very cheap ones are probably history. It doesn't hurt to check... but the rail pass allows any trains you like at any time you like, and you can even buy it in Germany if you like.

https://www.bahn.com/en/view/offers/passes/german-rail-pass.shtml

Shorter trips of course will cost a lot less by train, and normal ticket might make sense in that case. It all depends on your journeys.