More than gaidens about those things i would like some flashbacks, the things i would like to see on gaiden (even if they are 2 chapters) are:

1- Sannins, how they grew trainned and get separated, the fight between jiraya and orochimaru when he left should rock (not like the fight they had with tsunade,shizunne,kabuto and naruto, without jutsus and handicaps).

2-The 4th when he became hokage, i want to see some hokage life, their jobs and missions, fights with other hokages and so, how he fought kyuubi and who was his girl that gave birth to naruto (this could be wrong but looks like it is going to be this way).

And some flashbacks about the ones u said and kabuto.