Since your spreading fire effect is to be used in a staged cinematic, you dont have to worry about blueprint and scripting this would be done with a sequencer.
The way that I would approach this would be to make a torch fire particle system which I would attach at the tip of the torch, then I would create a “Hay Fire” particle system which I would place on the hay pile and when the animation of the torch reach the hay pile, I would activate the Hay Fire particle system at the proper frame in the sequencer. I would also create and place the wooden stake fire effect which I would activate after a couple of seconds of the activated hay fire. You can also place many hay fire particle system and activate them subsequentely to give an illusion of spreading fire.
So basically 3 custom particle systems activated at specific timing. I would probably animate some shaders parameters as well on the hay and the wood to give a burning look.
The question is pretty large but I hope that it gives you some hints!
Cheers!