Will using Jt baker 85%KOH to dry ether/amine do any damage to the freebase?Ie. over basification.
It won't hurt MDA, MDMA or methamphetamine.
Will the 15% h20 in the KOH have to be removed to render it proper for drying?
No, the water that is present in the pellets as they come from the bottle is not a problem.
As Chromic says, anhydrous MgSO4 is better. It is quicker because it has more surface area than the KOH pellets.
Do not use CaCl2 or even silica gel or alumina.
Especially do not use Anhydrone!!