Question, I have the P4P+ with controller GL300E, and it is ok. I understand it is an android system.  A/C and controller have the most current update, and performs very well.
If I purchased the GL300F controller, then used my Ipad 9.7", 128G, with cell service, iOIS would I be able to then link the controller to the A/C, and use it that way.  Possibly using 3rd party apps?

Then should I want to use the GL300E again, just relink it.

Yes. You can do exactly that. Cell service is not required, btw.