We had a thread on this not so long back. 'The blinds' are the baggage car behind the engine, blind because the forward end door is locked.

Riding the 'rods' refers to the gunnels or iron bars that act to brace the iron frames of old boxcars. They were located about 18 inches below the car, giving a hobo just enough room to climb in on top of them, just a few inches above the sleepers.

John the Conqueror is a root used in hoodoo charms.

A 'rider' more generally referred to either a woman ( deriving from the term to 'ride', ie have sex with) or a guitar, because of the resemblance of the shape of a guitar to a woman. Robert Johnson sang:

Lord, I'm goin' to Rosedale, gonna take my rider by my side
We can still barrelhouse, baby, 'cause it's on the riverside.

Brian