I didn't write any guide about Phoenix in particular because is quite simple to use. I don't think is needed more explanation. In my comparison guide is already included and presented all the functionalities.

Phoenix is a LN node, is a "private" node, that uses trampoline channels, like Electrum. That means you cannot route others payments through it, only yours. Your Phoenix node will always be the outer rim of the LN galaxy.

Yes, your LN node will be active only when you start Phoenix app.