Maximum Number of Zones

[astrogerard]

Following these directions it looks simple enough.

Can I use a solderless breadboard or is a perf board recommend?

What type of pin headers do I need to purchase?

What gauge jumper wire do you recommend?

What type of power module would I add to the breadboard to power the relays?

Thanks again for all of your assistance.

Sorry for the late reply... had some other stuff to do...

Dan already showed a nice solderless board but if possible I would use a perfboard and solder some IC sockets for the shift-registers. In my case I try to solder as much as possible but must admit that I'm also using jumper wires. 
Some "design-principles" for me are:
- Long term support and opensource software  --> SIP does so. Support from Dan is great and in case he wins the millions the code is still readable an with some Python knowledge you(we) could continue the project
- Long term support on hardware --> hardware like the Pi, relay-boards, IC's, PSU's etc. must be simple and easily to get so that replacement is easy when necessary. I live in a country where several times a year we have huge lightning so sometimes "components will change color and start smelling bad" :-)  
- The setup should be fairly tolerant to a humid climate --> Solder of crimp as much as possible. In case of jumper wires use hot-glue to fix and protect against moisture
- use separate power supplies for the Pi, relays and valves. Since the (right) relay boards have optocouplers there is separation of power and logic. --> for the 5v relays a 1 or 2A usb charger can be used (I do so for many years)
- The master-valve relay can be used to switch on/off the transformer for the valves (reduced power consumption)

All items are easily available locally or via the well known Chinese webshops.   

--Gerard