Those marks on cylinder walls. You said you could feel one with your finger nail. Those are usually due to FM(foreign material) and the rings/piston skirts rubbing them in. You can run with them for a while, just know that oil will blow by them somewhat depending on how deep they are. The rings won't settle into them or anything.
Hard telling how long you will get away with them like that but that is a sure sign that you will need a rebuild in the near future. I would think with fresh rings you might have 40,000ish miles maybe more on a daily driver before you see any real problems. And most likely your just going to be using more oil at that point. Might go to 70,000 before failure.
If you run it hard though at 40,000 miles she will be shot, if it lasts that long. You will see compression loss at this point and maybe even ring and/or cylinder failure.
Depends on what you plan to do with the car. Harder you run it the worse that cylinder will get. The worse it gets the more heat it will generate (hot spot) and cause premature wear leading to failure.