@Murph72: got you. Yes, you can set up TL-WR70N as ‘Access Point’. Then connect OpenSprinkler to it via Ethernet cable, and iPhone/iPad to it via WiFi. As long as you use the OpenSprinkler mobile app, you should be able to access the controller without any Internet connection.
Ah, just as I finished typing, I noticed BinaryOS has already responded to both your questions 🙂