Jeff,
Yes, the 87a terminal is to use the relay in a normally closed manner, you want to leave that empty and use terminals 87 and 30 to give you a normally open circuit that is closed when activated.
Yes, the relays are necessary to avoid the need to change wiring at the helm and running new wire to the bow locker. To prove my theory on your boat, use your volt meter and pick up the negative anywhere up front in the Boxtron, and read the voltage on each of the original wires coming from the helm. When the switch is activated in each position you should see +24 volts on the corresponding wire. You do not want to apply that voltage to the terminals 4, 5, or 6 in the e14s or you will damage it. To test the other end of the circuit, hook up the e14s with power in and power out. Nothing is happening, but then use a jumper wire (no power) to connect 4 to 5, you will see it turn one direction. Then jump 5 to 6, you will see it run the other way. This is clear on the wiring diagram on the cover of the e14s.
On your note about the switches that activate in the full up/down position, I think you are referring to limit switches, the little blue plastic push button switches. Yes, I have purchased them from RS Component in the UK. Their web site is: http://www.rs-export.com/ and their part number is 223868. Yes, these are the exact same manufacturer that Amel buys from, but RS has them in stock and will ship right away. Amel buys them and solders the wires on (usually on the correct positions).
Bob