Well, I a galaxy far, far away; collars and cuffs were detachable from you shirt. These were specially treated cotton and could be replaced easily with a few buttons affixed to said shirt (since the collar/cuffs are the one getting frayed first...not the shirt itself).
Thanks to our Italian friends; they thought that collar + cuffs should be an integral part of the shirt...hence, when those pieces are used and worn, you'll have to buy an entire shirt instead of those replaceable pieces
As for rolled-up cuffs, there's no definite protocol as to where you could roll them on your arms. Some prefer one roll on the forearm, others higher. It's personal. Surgeon/doctors have a tendency to roll them up high (past the elbow crease) when performing some kind of operation on a patient...
I hope you don't have to go that far in your personal life