I don't know the solution to the site rebuild issue. I'll see if Netlify starts failing me at some point.

As for the web UI - you've got one! Well, I've got one. Since I use Netlify linked with GitHub, all I have to do is edit the file in github. Now, I can do that using github's interface, which isn't jekyll friendly, or I can use prose.io, which has a beautiful interface and hides the metadata so you can focus on the text and can easily fix mistakes or add content to existing posts. (it even let's you edit the metadata separately, which is a pretty complete editor!)

What do I do for creating new content? Take a look at this file - https://github.com/nitinthewiz/TheLinkBlog/blob/mine/cms.html

It's a hack from a guy named Vrypan that uses a JS library to talk to github.

The interface looks like this - https://notes.vrypan.net/cms.html

His initial blog post about it sits here - https://blog.vrypan.net/2015/05/29/post-to-github-jekyll-using-a-bookmarklet/

As you can see, it requires your github username and password, but it's using SSL (and you can too, if you host using netlify), so it's somewhat secure.

His version takes post title, text and tags, while I've modified it to take link URL as well. The cms page is rather mobile friendly and I've used it in a situation or two.

I don't know about comment system. I've seen so many come and go, first with app.net and then some in its aftermath. But if people don't find any, they just replace those with a comment on twitter or m.b

Cloudflare caching is nice and helpful, but in the case of WP, I've not seen them save me more than, say, 35% traffic at any time, by their own measure. But that's better than nothing!