Basic concepts

TouchDAW is made up of two functional layers: A DAW controller plus some general purpose MIDI tools. It's effectively two apps in one. These two parts are independent from each other and can be used completely separately: Each part may connect to separate target applications eventually even running on separate computers. Most likely though, you will end up using them in parallel, talking to the same program: To record MIDI in the controlled DAW, prelisten or trigger samples, maybe interact with synthesizers using MIDI generated by the phone's accelerometer or whatever else may come to mind.

DAW Controller

The first functional layer - and the app's default startup screen - is the DAW controller. It is functionally compatible with a Mackie Control Universal (MCU), which has become the 'de-facto standard' hardware control surface for most DAWs and gives you control over a large set of parameters in the controlled software. In particular you get control over the DAW's mixer (track volume, panorama, automation, solo and mute settings), transport, effects, equalizers, virtual instruments and bus assignments. Additionally you will be able to save projects, perform undo's and redo's etc.

What exactly is accessible depends on the controlled DAW and its Mackie Control implementation. TouchDAW does neither define that functionality nor can it change much about the way your DAW's authors want their product to work with a Mackie Control. The app's DAW presets are primarily relevant for the phone interface, where the number of controls and the screenspace available for visualizing information is limited. On tablets they do little more than to relabel the buttons in the master section. In any case it is very much recommended to read up on your DAW's Mackie Control support in the DAW's manual.

MIDI Utilities

The second part of the app is made up of some general purpose MIDI controllers. TouchDAW includes a multitouch keyboard with pitch and controller support, a MIDI mixer, multitouch launchpads and xy controller pads that can also map a phone's sensors to MIDI controllers.

Two MIDI connections:

Both parts of the app are independent from each other and use seperate MIDI connections.

When setting up MIDI connections it is important to understand that the DAW controller essentially requires a "closed circuit", bidirectional MIDI link between the app and the DAW. No other MIDI source should interfere with the communication between the two and you will want to keep remote-control data away from your "musical" data flow alike.

Performance, battery use etc.:

TouchDAW can potentially generate a lot of traffic over WIFI and as it is dealing with music you will want it to be fast and responsive. Keep in mind that on smartphones there are a lot of other things happening next to the app currently running in front. For best performance you should consider turning off things that are not currently needed. Don't let the phone download email or check your friends' facebook status when you are performing on stage or recording.
MIDI communication over RTP requires a constant uninterrupted WIFI connection. A lot of phones shut down WIFI when going into energy saving mode and thus will break the connection. You may need to let TouchDAW disable sleep mode and have your charger at hand when using the app for longer periods.