Importing a large catalog with many EAVs considerations

Background: we have an existing 2.4.6 site that’s working well with a few hundred products and a few EAV options(length, width, color, size). We sell specialized industrial products so I’m not worried about traffic spikes or many concurrent visitors. A supplier has recently offered us access to their entire product dataset, but it’s about 200,000 simple skus, with maybe 1500 attributes and 3000+ values. Many should be switched to configurable products by some of the EAVs for easier navigation.

Questions:

• Is this something I can reasonable import without problems? I’m looking into import plugins and I read the adobe article about EAVs and mentions limiting them for performance but doesn’t really offer any guidance about what that means.

• Will indexing be a problem? Other than maybe a weekly price update I expect the catalog to be fairly static.

• Is there any difference between text and drop down EAVs? Am I better off with one dropdown with hundreds of options like box of 10, box of 20 or one dropdown with words like box plus a text box for 10 or 20?

• Are there any good strategies/plugins/software for doing simple to configurable, besides manually?

Appreciate any insight anyone can offer! Also if anyone has any good resources about largish catalogs I’d welcome those too. Most I’ve found have been super-unspecific seo style blog posts. I realize there are a lot of variables like traffic and server specs but I’m trying to figure out if this is doable.