Ok, the first one, yes weather and favor increse the farms production so, if you cast them you probably destroy some farms and build some towns, then your income will growth, and the effect of weather and favor get "plused" i mean is weather + favor if you cast both of them.
Resist element reduce the damage made by elementals (elementals are efreetis, ice elementals, etc, race=elementals)
At exception of mind bar green proteccion can`t be raised, red proteccion also can`t be raised.