Go to you tube, search Brent Walston grafting pine.
Also go to resources section of BNut. Search for the tutorial on grafting.
Also go to the "Grafting, Layering and Propagation" sub forum of Bnut. Many threads on different styles of grafting.
Every question you asked have been answered multiple times in those 3 locations. I'm not trying to be a jerk, just trying to limit the amount of repeat typing I do. It takes hundreds of words, a long essay to write out how to properly graft, and have success.
Timing is important. Winter - late, just before scion and understock begins to wake up. If new candles have begun extending, it is too late to graft. This applies to both scion and understock. If either is growing it is too late. A second acceptable time is just before the autumnal equinox, though this is not as high a success time. About 3 weeks before the autumnal equinox through a week after the equinox.