No. They just thought that some Slavs who looked like Germans could be "umvolked" (that's a term the extreme right of today uses for "exchanging European people by Third World people", but the original meaning was different). They got German citizenship (provisional only), had to learn German and so on. This included kids who were taken from their families.
No.
As someone noted elsewhere the Polish side of town was classified as the "Aryan" side. Slavs (or at least West Slavs) were deemed to have originally been Nordic, but there was considerable intermarriage with other groups that the Nazis really disliked. It wasn't that they looked like Germans, and so could be assimilated. It was that they looked like Nordics (because they
were Nordics) and so would actually be making Germany better by being brought into it. There was a lot of shifting around regarding the how Germany was to define Aryan - with the general thrust for practical purposes being to render it essentially synonymous with German or Nordic ("tribally related to German blood"). Of course those theorists also had a great deal to say about the supposed criminality of eastern Germans - which they blamed on said "Inner Asiatic" blood - but those folks were still Germans and hence Aryans though (even if they may have been deemed to be less Aryan and generally worse than the Polish children who were being set to be Germanized).
That's the thing, the Slavs may have been deemed subhuman but that doesn't mean they weren't thought to have been of Aryan stock originally- merely that they had intermarried with Asians and that Germany wanted their land. So a small group of Slavs who were thought to be descended from the Aryan upper strata were eligible for Germanization. Similar issues were found in Germany though, the trend to idealize the Nordic had obvious issues given that many Germans, particularly in the south weren't really Nordic even though they were undeniably German. But in terms of long term theoretical goals the Nazis wanted to purify the German race too and integrating those Nordic Poles was part of that.
In general, official German use of the term Aryan was recognized by the Germans as being narrow and not precisely accurate - and was generally defined as being in relation to Germans not to "Aryans" more generally - for instance the Nazi Office of Racial Politics classified non-Jewish Turks as Europeans and Iranians were officially recognized as Aryans (despite this running directly against some earlier Nazi racial theorists ideas) for both practical and theoretical reasons.
Ultimately I'd say the focus on instrumentality vs. theory can be mostly clearly seen in how Croats and Bulgarians weren't subhuman but Serbs were. But like I said, in terms of the more serious, broader view on what an Aryan was Slavs were deemed to be Aryans but not pure (but then, neither were most Germans). In terms of the more narrowly defined meaning of Aryan it basically just meant how closely someone was tribally related to the Germans which although used at times still put Slavs as more closely related to the Germans than most other groups on Earth (although much less so than pretty much any other Europeans). I mean, it's not exactly the most coherent of systems regardless of course but even with the narrow definition of basically just being German many Slavs were deemed to be eligible for assimilation.