I'm not sure why you have all of these issues. In fact, you shouldn't even really need root to do any of this at all.
1. Do you have your com.popcap.pvz2 (could be called something different) in Android > OBB?
2. If so, then install the PVZ2 APK, and it should work without a problem. Otherwise, your OBB files may be corrupt in some way, shape, or form, and you'll have to redownload it all from another source. I highly recommend downloading for a computer and then transferring it over, as downloading directly onto your android device is not always reliable, unfortunately.