1. Are there any of your 5-star ninjas that you would be interested in having skillbroken? If so, hold those frags for when they are available for skill breakthrough. Otherwise, you can save for the 30k refine frag and get yourself 8 seal scroll/16 summon scroll (and a naruto 9 tails frag) .

2. I assume you have drawn kirin from summon treasure. If not, I would recommend waiting to see if your first summon super rare is KOH. Else, if your runes are maxed-out or close to maxed-out, why not get them KOH frags :).

3. It is not exactly clear when shisui will be coming, but if you really want to save for him, go for it.

minimum, as much as masked man/jonin minato. Will most likely be more.