Re: String recommendation?
if you have arm problems you would generally want to go with a multifilament or gut string, a thin gauge and a lower tension; the combination of which isnt conducive to topspin and control.
one option is to go with a multi, such as nxt or xcel, or a gut. that will give you a comfortable stringbed. to get spin and control you would simply string at a higher tension.
another option is to go for a hybrid of a poly and a multi or gut, but have the multi or gut on the mains. the mains are the primary influence on the stringbed, so having the multi or gut on the mains will give you comfort, and having a poly on the cross will help with control and spin.