I want to migrate away to another provider (one whos devices last more than 2 years).
I have an iPad 1 and an iPad 2 both still on iOS 5.1.1 and haven't yet run into an app they can't run. I'm sure there are a few that require iOS 6, but there aren't many, at least as of yet. But if you insist on changing platforms, I'd suggest you avoid Android tablets, then. They are tending to provide OS updates for even shorter a period of time than Apple does. What Microsoft will do with the Surface remains to be seen.
How do I convert the music that I purchased through iTunes to MP3 or another media format?
I'm sure there are also a number of other applications for Windows that can convert audio tracks.
The link you sent through is for a much older (and better) version of iTunes. As much as I hate the latest release, you simply need to right-click on your tracks and there's a convert to MP3 option.
There are plenty of new apps that require iOS6 already and any new ones are likely to be written expressly for it. I only realised today because an App I wanted was only for iPad only and required iOS6.
I think it is absolutely remarkable that Apple cannot write an OS that works across different hardware platforms, but then they're also the company that can't program and alarm clock so I shouldn't be surprised.
The instructions still work as given. If you are using iTunes 11 and don't see the menus, press Control-B or go to the small icon with the arrow at the extreme upper left and select "Show Menu Bar":
Or again look for a third-party format converter, of which there are several.
I think it is absolutely remarkable that Apple cannot write an OS that works across different hardware platforms,
They certainly could if they wanted to, but unlike Microsoft and Google, Apple makes their money off their hardware, not their software, and hence restricts their software primarily to their own platform, a model that Microsoft at least is now starting to copy. But by all means purchased whatever device/platform you think would best suit your needs.