Re-string service - Squash

Polyester gives control, spin and durability, and suits players who swing fast and break strings. Multifilament is softer and more comfortable, which suits players with arm problems or slower swings. A hybrid, polyester in one direction and multifilament in the other, is a common compromise.

Yes. Thinner strings bite the ball for more spin and feel, but break sooner. Thicker strings last longer and play a little duller. Gauge is measured so that a higher number is thinner, which catches people out.

Lower tension gives more power and comfort, higher tension gives more control. Every frame has a recommended range printed on it, and starting in the middle of that range is sensible. If you are getting arm pain, drop the tension before changing anything else.

Almost certainly. Strings lose tension from the day they are fitted, so a racket strung two years ago plays nothing like it did. The old rule is to restring as many times per year as you play per week.