First, please note that the ToneWoodAmp is a stand alone device that has its own DSP for effects (reverb, delay, echo, tremolo, etc.). No iDevice or Android device is needed for these effects to function.
Android apps that offer guitar Effects and Amp sounds, like Amplitube, can be used with Android as long as you have the correct third party hardware (iRig). The Output Jack (DI Mode) must be used for this and the output from your hardware (or headphone out) is fed back into your TWA via the Insert Jack. For best results, be sure to set DI mode to TWA and DI.
In theory, the iDevice Midi features will work on Android, but the problem we're currently facing is the Android platform does not, at this time, have any apps that support Polyphonic Virtual Midi, which is required for Midi apps to process the sounds of other instruments back to the ToneWoodAmp in real time.
With iOS and MIDI Sampling, a small audio signal from the insert jack is used to create a MIDI signal (not an audio signal, like effect apps on Android), which is then processed as different sounds, not effects, and sent back to the ToneWoodAmp via the Insert Jack.