Dark Souls II: Scholar of the First Sin - PlayStation 4

Q: Will your save data transfer over?

If you have the pc version it is simply a patch but since the there is no ps4 edition before this your save will probably not carry over same goes for x360. But there will be a patch for ps3 that you can get that is exactly this. http://www.designntrend.com/articles/33514/20150105/dark-souls-2-director-reveals-content-details-of-scholar-of-the-first-sin-update.htm

Q: Is the dlc included on the disk, or does the game include a digital code? Can i buy the game used and still get the dlc?

It is right on the disk there is also new enemy placement to look forward to/dread.

Q: Does it include Dark Souls 2 full game o just the 3 dlc's?

You get the disc for "Dark Souls II: Scholar of the First Sin", PLUS 3 DLCs for "Crown of the Sunken King, Crown of the Old Iron King, and Crown of the Ivory King"