When do the radaitor hoses needs to to be replaced? The stock one seems fine.
I have a leak in the power steering transfer hose (under the car on the passenger side). Can that be replaced with a regular black hose from the auto parts store?
Radaitor hoses should be replaced when they become soft or the least bit mushy.
No, PS hose requires a high pressure rating above 1200psi; ask for PS hose specifically at an auto parts store.