I do think that it might be possible that Dutch policymaking would be changed if the Dutch state was intrinsically different from OTL, as a territorially larger state with a much larger population and much more industry. This would be a quantitative change of such a nature that it would be qualitative; the United Netherlands would approximate the stature of a European Great Powers in a way that the Netherlands and Belgium did not OTL.
This does not mean, mind, that there would automatically be an interest in direct competition with the UK.
I would largely agree. With the southern Netherlands, including but not limited to Francophone Walloon areas, being an obvious target for French irredentism, the United Netherlands would have an obvious interest in alliances that would protect against France.
What could France offer? There is the Piedmontese scenario, I suppose, the weaker neighbour making territorial concessions to arrange in exchange for French support in realizing their goals elsewhere, but what would this involve? The Walloon provinces, especially given their industry, are relatively much more important to the United Netherlands than Nice and Savoy were to Piedmont. Beyond that, what is the United Netherlands supposed to cover? North German hegemony?