CasioMens Quartz Watch, Digital Display and Rubber Strap GWM500A-1CR

Does this watch ever pinch your arm hairs occasionally? My old G-Shock which is finally beginning to wear too much in the band, always does this

How do you change it from a 12 hour format to 24 hours?

what's the left hand side indicator on top where the little triangular indicators appear & dissapear with the seconds for?

Can the band be replaced with the nylon nato/zulu straps ? has anyone actually replaced the band with one that isn't cheap plastic or rubber?