A - Most RF meters actually measure electric field (in V/m2 units) and then calculate the RF levels (in mW/m2 or uW/cm2).
This calculation is possible and correct only if done in the far field.
Therefor if you use a RF meter to measure RF from a cellphone right next to it you will not get the right levels.
What you can get is an indication that there is radiation (and this is what I try to show in my videos).
In order to measure the RF from a cellphone you need to measure it in the far field and then to calculate the levels that are next to the phone.
An other may to do it is to use electric field meters (I have 2 and in some of the videos I use them).
But this is not the end of the story.
Cellphone emit high RF radiation in high frequencies (most of the times more then one frequency) but also low frequency electric and magnetic fields.
You need also to measure them and to take them into consideration.
Measuring all the levels in all the frequencies emitted by a cellphone is very problematic and very complicated.
Please see the following videos:
Video clip:Different types of radiation from cellphones