SV3-16-O Series 2-Way, 2-Position, Normally Open Solenoid Cartridge Valve, Housing: None, Coil: Not Included

Coil and housing are not included with this cartridge. It is the SV3-16-O-0-00 screw-in cartridge only, and it uses a J series coil (23 W) that is sold separately.

Correct. In the de-energized state, flow passes freely in both directions between port 1 and port 2. Once you energize the coil, flow from port 2 to port 1 gets blocked. Flow from port 1 to port 2 is still allowed after spring force is overcome. So yes, losing power means the valve stays open, which is something worth accounting for in your circuit design if a fail-safe closed condition is what you need.

In the de-energized state it is open in both directions, so flow can go port 1 to port 2 or port 2 to port 1. When you energize it, it blocks flow from port 2 to port 1, and it will allow flow from port 1 to port 2 once the spring force is overcome.

Correct. In the de-energized state, flow moves freely in both directions between port 1 and port 2. Once the solenoid gets power and overcomes the spring, flow from port 2 to port 1 gets blocked, while port 1 to port 2 remains open. So if you lose power or a wire comes loose, the valve defaults back to flowing. That behavior is worth keeping in mind when you're planning how it fits into your circuit.

This SV3-16-O series valve should be a suitable replacement, assuming your existing setup uses a 2-way, 2-position, normally open configuration. Just make sure your flow and pressure requirements are within its 60 US GPM and 3000 PSI limits.