Liquidation questions

Hi, i have some questions about liquidations:

  1. When I can liquidate a borrower? when health < 0?
  2. I can find the debt reserve address, but how can i find the collateral reserve address?
  3. I tried to tranferDebt of a wallet with the following tx but it is giving me the error:

Error: Error while executing account-script: transferring debt: breaching liquidation threshold(bp=73499, bpu=105263, health=-433)

TX JSON:

[
{
“type”: “string”,
“value”: “3PEiD1zJWTMZNWSCyzhvBw9pxxAWeEwaghR”
},
{
“type”: “string”,
“value”: “3P8G747fnB1DTQ4d5uD114vjAaeezCW4FaM”
},
{
“type”: “string”,
“value”: “3PG2hfKakD4TmpQ3znzoHp7nY54idkrT33z”
},
{
“type”: “integer”,
“value”: 10000
}
]

I would like to know too, I was not aware we could liquidate someone