WASHINGTON — Robyn J. Skrebes of Minneapolis said she was able to sign up for health insurance in about two hours on Monday using the Web site of the state-run insurance exchange in Minnesota, known as MNsure. Ms. Skrebes, who is 32 and uninsured, said she had selected a policy costing $179 a month, before tax credit subsidies, and also had obtained Medicaid coverage for her 2-year-old daughter, Emma. Read more....