Migration from ESA Support to UC

Hello
I am the mum of a 24 year old who has been on ESA Support since aged 18 and also on PIP. We have had the dreaded letter about applying for UC , my son is in no position to do it so it falls on me as do most things,

I have his passport will that be sufficient for ID purposes?

Will they ask for any of his bank statements? he has an account but no statements as it is all online banking

will they ask what outgoings he has? he pays money to me to cover bills etc but he gives me the pip to cover that not the esa , do i still put that as outgoings?

why cant they just transfer over people without making them apply again?

is there a copy of the UC form for me to look at before i log on and start to answer it so i know what questions they will ask?

thanks

David,
on the form it asks if you are completing it for someone else so assume i tick yes and then can i add my email and phone as son will not respond to his