As your core team sees more and more common modules being written or used, they look for things to add to the core extensions. In some cases, the developers would love to volunteer their code to the core extension team, under the same terms as the language itself. No conflicts, it's just a gift.

As far as implementation goes, you make sure your core extension code is as solid as primary code and tell people that core extension modules are preferred. You even make it easier to do it right than to do it wrong. Your compiler could download new core extension modules as it needs to or you can put them in a special place on disk. You also want to keep updates infrequent and interface changes not happening at all. That way your code written on PHP 5 and abandoned by the developers but there's too much data to risk migration to another platform can keep working. (Yeah, UCL's phpBB is way out of date.)

You're probably right. Android is fairly stable which was one of the things that Windows 9x didn't really have. An application crashing could take the whole system down. I rarely see that on Android (and apps are more stable, too). Come to think of it, NT's gotten so good I can't remember the last time I had to power off a PC to get back control of it. Android's been somewhat recent, maybe about 9 months?

Phones are getting ridiculously long, why not use some of that space for navigation? I can afford a little space for knowing how to get out of a very often used mAPP, like Google Maps. Sometimes... Ugh.