RE: Collecting Social Security. The Social Security website
http://www.ssa.gov has a very good calculation program. It can tell you how much you will get per month at various ages using your actual data. Income goes up every month you delay and program can only do by year but it is a good starting place. Medicare starts at 65 don't miss application date, because your cost goes up every year you delay. You can start the paperwork a couple months early and I would recommend it (Just had my first medicare doctors visit Tuesday). At 63 or 64, medical insurance can be very expensive, if available. My husband worked long enough to make sure we had access to his health plan until we were both 65.
Make sure your plans coincide with the Grandbaby's parents. Our son lives about 30 minutes away. Far enough that we are readily available for emergency babysitting or the fun stuff but not everyday. There is a reason that women our age don't get pregnant. Hauling 20 or 30 pounds of wiggles up the stairs is a lot harder than it was when I was 35.