Hi.Sounds like you need to loosen the truss rod and try a set of lighter strings.
Hi,by changing the string size you have increased the tension on the neck, and the truss rod must be loosened. Also are those strings sitting in the ...
sthe tone pots are not grounded by the picture
yes,the middle position is for both pickups.
You could try loosening the truss rod a quarter turn,Epiphones are famous for the neck tightening up.