The due date for 0.5x is mid June-ish, although we have a ton of cool things in the works aside from this so it might be pushed a week or so beyond that. Can give you a better estimate once we start rolling stuff out, @baris already has the initial version out for the tag system for example
Shouldn't this request be directed to Taptalk Inc? They seem to charge both the app user and the forum maintainer for "pro" features.
As this is an open source project, they're free to provide a NodeBB taptalk plugin and earn more money
We do offsite installations and upgrades, message email@example.com
Of course, we do have docs so you should try it yourself just back up everything first!
Edit: to answer your original question, we do plan on building an upgrade button into our hosting plans control panel - right now we just upgrade customers manually. It's probably impossible (or hard) to make an app upgrade itself via acp, we would need to make the acp a standalone application (we've toyed around the idea, but not worth the development time)