Well probably nothing would happen to Nagato but that body of Pain would be completely sealed, so unless they retreat, the King of Death could not repair it and they’d be down one man. Totsuka should be able to seal anything really.

It isn’t his real soul so it wouldn’t have any affect on him physically but mentally yeah he’s absolute bonkers over deva path he even sacrifice his other paths to save it

It would just kill the path

It's not known what would happen. The manga mentions something about sealing targets into a genjutsu-like world of drunken dreams. While also showing the TB slice through objects and not sealing it. So, it's implied that it only seals targets with consciousness. So, I'd guess it wouldn't seal the Pains .

It will suffer from physical damage only the sword sealing wouldn't work