WellieSTR(2 Rolls) White AND Black Elastic Thread 547 Yard Package 0.5mm Thickness

How do you find the tip/end of the thread?

Can this elastic thread be used with a sewing machine?

is this steam activated and goes in the bobbin ?

I am wanting to use this to restring holes on "shredded" stretchy jeans where the strings are breaking. Will this work?