2 problems - very poor signal & transfer apps issuse

Hi I bought a s3 which is not rooted, and I'm trying to transfer my files from my HTC Tunderbolt which is rooted, but without success. I need a walkthough please that works. tried a few always stuck at the point where the microSD card can't be read. I know it works so that's not a problem. Finally has anyone been experiencing poor signal with the s3? My friends are always complaining they can't hear me or I sound low or muffled. thanks in advance for any help.