My question is, if kekkei tota is a bloodline limit, then how did the 2nd tsuchikage (Mu) teach it to Ohnoki the 3rd tsuchikage (who are not from the same bloodline)? Or does kekkei tota work differently than kekkei genkai?
There's no indication that it's ever specifically stated one way or another that it's hereditary, and given that two people without any blood relation have it, it can be assumed that it is not hereditary. Rather, based on Shippūden episode 268, it seems that what is necessary is, at the very least, for the users to have an affinity for all three elements that the kekkei tōta uses. However, as Dust Release is currently the only known kekkei tōta, it's hard to say if that is definitively the only requirement. The Naruto Wiki addresses this.