These are indeed authentic Clarks. I usually wear anywhere between size 9-10 in shoes, and the 9 in Clarks fit me perfectly.  My issues: wide feet, flat feet, sensitive toenail beds
The Clarks: a little tight around the sides and toes at first, but I broke them in by wearing them for small amounts of time without too much walking, then increasing the amount of wearing time/walking. I don't remember how long it took to break them in, but it was a reasonable amount of time and now they are wider and the toes have more room as well. My very, very flat feet are not pained any more by these than by other shoes that are not built with insoles.
DO NOT wear around moisture/rain/snow/water/kitchen/barn/swimming pool or anywhere where even a drop of liquid can get on them- it will stay on the suede! (and then a professional cleaning will be in order).  They do naturally darken a little, but not in a "dirty" way.