Loan from spouse

Yes... You can any of the above said One if You book the amount as Loan.

Thx
Any prescriber format ? Whether external witness sign required?
I m thinking to document it on simple paper.
Some amount was returned so I did not treat it as gift as gift are not reversible as advise to me. But practically can't we treat it as net gift or gross gift to each other.
Should I now document the gross loan fugure on simple paper for a record ?
Whether document need to be notarised ?

As per my view No need for notarized...

Also no more specific formats. You can prepare Yourself with details.