Those are great questions to ask here! Providing a place for such discussions is one of the goals of this community. We have some guidelines for asking non-code questions: FAQ: Tips for Introducing Non-Programming-Problem Discussions
But please don't use the #meta category for such topics — #meta is for discussion about this site, its organization, how it works, and how we can improve it.
I think right now non-code-specific questions about data visualization theory & practice fit just fine in #general — but if there was something very #tidyverse specific about the work you are doing (for instance), the question could also go there. I think the key element is to make clear up front that you're not asking how to implement something, you are looking to open a more general conversation about data visualization practice. The FAQ linked above has some more advice about how to tag such topics.
(Edited to clarify my antecedents 
)