You can create a separate blog for your microposts, or you can integrate microposts into your existing blog using a category or tags. You can create an RSS feed for just that category or tag (here’s how). You can create a post without a title. You are able to export your site in WordPress format (only one blog will export).
You cannot post with a 3rd party app; Squarespace apps don’t even appear in the Share sheet. Squarespace’s 2 posting apps are feature-limited. Their Note app would be great (simple interface, pull-to-send), but doesn’t leave the title blank, doesn’t recognize Markdown, doesn’t allow categories to be applied (I’d be happy with a set-and-forget option), doesn’t offer a character count, and doesn’t cross-post. Their Blog app is overly complicated, has a janky Markdown entry box (just like the website), with extremely limited cross-posting ability.1
WordPress seems like a more complex option, albeit more customizable. I’ll be interested to see if moving to WordPress is worth it once Micro.blog gets going.
If you use the built in Twitter sharing, it only shares the link. If you use iOS Sharing, you have to copy your post beforehand if you want it to appear in a tweet, etc. ↩