It's hard to find a view that shows only posts from my subscribed subs.
The list icon next to the search and the new post buttons. It opens a dropdown with a link to /sub (the view that shows only posts from your subscribed subs).
You can change your homepage to the subscribed view in the account settings. That way clicking on the kbin icon in the top left gets you there right away.
What even is a Microblog?
The mastodon/twitter type of thing. The Microblog tab enables kbin users to interact with mastodon users directly. I think it pulls in mastodon tweets that use tags defined by the moderators?
Am I posting a post or a microblog thing right now?
The naming is a bit very confusing currently, I agree with that.
kbin uses "article" as the term for a text post, "posts" go into the microblog section. Which is where you posted to here.
I assume that naming was probably chosen because of the magazine theme, so individual posts within a magazine are articles.