The Arduino software is used to write a "sketch" - basically a script - compile it, and send it to your Arduino board. It is also used to receive data from the Arduino board in the form of the Serial Monitor. Here is a download link for the software and an overview of making it accessible.
No adjustments needed. You may like the Arduino O&M post for more details on the smaller parts of the board.
If you are using OS X, VoiceOver has been reported to work with the Arduino Integrated Development Environment (IDE) without modification.
If you are using Windows, see this post about setting up the software on Windows.
If you are using Linux, the Windows setup post may be helpful but we do not have further details at this time.