Moving the Beacon is pretty simple.  You will need their adapter cable to go from the EZ500 (9 pin DB9 connector) to the Beacon.  The CFX is direct plug in for the CFX/FMX Beacons.

There are two versions of the Beacon, the FMX/CFX version and what they call the generic/372 version.  They are identical in every way with the exception of the pinout. 

You didn't state it exactly but it sounds like you want to move the Beacon from the CFX-750 in the planter tractor to the EZ-500 in the sprayer tractor right?  The adapter they offer for the EZ500 is pinned for the 372 version of the Beacon.  You would simply just switch the pins around in the Duetsch connector to match up with the FMX/CFX version of the Beacon if that's the route you go.  Pretty straight forward.  Or you could order a 372 Beacon, run the standard adapter to the EZ500, and get an adapter to go from a 372 Beacon to the FMX display.  You end up having to buy two adapters in that situation.

262/372     CFX/FMX    Function

Pin5             Pin5          RS232 Gnd

Pin6             Pin4          RS232 Tx

Pin8             Pin3          RS232 Rx

Pin10           Pin9          12v Pos

Pin 11          Pin8          12v Gnd

https://store.godigifarm.com/products/detail.php?id=BN2018  Adapter from 372 to EZ500 (needs modifications if using the FMX/CFX Beacon)

https://store.godigifarm.com/products/detail.php?id=BN2010   Adapter from 372 Beacon to FMX/CFX.

As far as staying in between the rows with an ez steer it depends on a lot of factors. How tight your steering is on your sprayer tractor, how fast you expect to drive, how flat your ground is and how well you "tune" the ezsteer.  For burn/fall spraying, obviously no problems there.  For spring post emerge, that might be getting close the the capabilities of the ez steer system depending on the above factors.  Personally, I think you would have better luck with an EZ Pilot but I know they obviously cost more.  If you are on flat ground with 14.9 tires and under 8 mph with a tight steering system, it will probably work (I said probably).  The key is tight steering and flat ground.  In the side hills, the EZ steer sort of falls apart.  Well, around here anyways.

I ran an ez steer on my combine for beans and loved it.  I ended up going full autopilot because I got a smoking deal on a used nav2 but the ez steer was leaps and bounds above nothing. I plant on RTK now and can come back and do corn on RTK as well without row finders.... that's nice!