Everything you have discussed is related to the firmware.
If you put the IP:Port in your address bar instead of the web app you will notice the native firmware giving you the same information.
As for the invalid IP, have you ensured your not using a local IP?
The interval duration is a parameter required by OpenSprinkler firmware. Using 0 prevents a program from running hence my advice about setting it high.
Update: My web app is just a nice front end to Ray’s firmware and cross compatible with Dan’s OSPi program.