you can actually merge this type into newegg_subcategory_list:

<meta_metadata name="newegg_subcateogry_list" extends="compound_document" ...>

note the extends attribute up there. when you use extends, it will create a new type automatically, so you don't have to create the newegg_list type again.

I don't think it should extends creative_work, since the category list seems computationally generated according to some metadata field. the reason why the amazon list mania extends creative_work is that it is curated by the user, and that curation requires putting some creative efforts into it.