SkechersWomen's Meditation - Rock Crown

what is the difference between a 9 and a 9M? I need a wide 9 shoe. Will this work?

I have pretty wide feet and the flip flop “tongue” the strap that goes between the toes, is always too short. Will these fit?

Is this sandals good for flat feet?

If my size is 6.5 what size should I order?