For the distances you should use ac equipment. Pushing low voltage dc over those distances would require pretty large wire. For ac the standard multistrand sprinkler wire will work fine. The pump can be wired just like a valve with a starting relay near the pump end. In opensprinkler set it as a master. It will then start the pump when tha valves open. You can set positive or negative timing delays for the master to make sure you don’t air lock the pump or valves.
1″ valves are pretty good for drip lines, beyond that size the price will take a large jump upwards because they are not the “common” type used.
Make sure the pump relay can use an ac signal to trigger, if it can’t full wave rectifers are cheap and common, just add one right at the relay.
Other than that it seems like you have the idea and hardware in place to run just fine with OS. You will need expansion boards to run 24 zones, and the master(pump) will use a zone, just keep that in mind when purchasing.