Re: how do i know that the battery is fully charged?
There should be an icon in the top right corner of your phone showing it charging (flashing) when that stops charging it will remain solid.
As for Battery Pro+, you'd have to send information to the developer and ask them why it's not working right. Keep in mind the update cycle for live tiles is every 1/2hr.
I personally use Battery but even that lately has been acting funny.