I really really want update 2 for my Lumia 520. I had WP10TP on my phone and uninstalled it as it was driving me insane lol.
What can you do? Nothing. They're supposed to release for some x30 phones, but for us older devices, we're probably going straight to 10.
The added features are pretty small, I'm not sure why those would be something you really really.
If you need an update, you can install another language and it'll go through the update procedure.
You can't flash to it since it isn't official.
Preview isn't redundant, its just far to early for anything to be released into it.
Insider is giving you 10 directly because its kinda luck and supposed to be that way mostly.