The very shortest you will ever run at OCS is 3 miles, and the longest you will run will be a little over 5. You will run every day, except for when you are on liberty. Yes, you do get about a 24 hour liberty once a week after week 3, (although your sergeant instructors won't actually admit this until a day or two before you secure). There is no pit in Quantico.
Also, with regards to running, the first 5 weeks of OCS is generally run only in go fasters, and the last 5 weeks is generally running just in boots and utes.