Featless. He doesn't scale to Sannin Level via statements as they were not as strong as they are in the series; he scales to featless Sannins. Impossible to tell.

Idk

Zero info.

@Dyss00 we could look into the timeline a bit, we know that Sakumo killed himself after Kakashi had already graduated, and Sakumo was most likely still in his prime at that time. Rin died during the 3rd shinobi world war so Sukamo killed himself before then, meaning that Sakumo exceeds that of the Sannin during the 2nd shinobi world war, putting him somewhere close to Hanzo's level. Hanzo being Kage level since his power is unmatched in the hidden rain, even being strong enough to possibly hold back the other villages Kage, since we know that up until the end of the 3rd world war, Kage were seen in the battlefield.

TL;DR he can beat Hidan ig

@Sonofseagods Good point. Idk if Sakumo scales to the Sannin individually or as a group, but if it is as a group then it should work perfectly. Sakumo ~ Hanzo > Edo Hanzo ~ Mifune ~ 3T FKS Sasuke > Hebi Sasuke CM2 should work then? That's pretty strong for mid Shippuden.