Android - Handle "Enter" in an EditText

I am wondering if there is a way to handle the user pressing Enter while typing in an EditText, something like the onSubmit HTML event.

Yes.

Also wondering if there is a way to manipulate the virtual keyboard in such a way that the "Done" button is labeled something else (for example "Go") and performs a certain action when clicked (again, like onSubmit).

Also yes.

You will want to look at the android:imeActionId and android:imeOptions attributes, plus the setOnEditorActionListener() method, all on TextView.

For changing the text of the "Done" button to a custom string, use:

mEditText.setImeActionLabel("Custom text", KeyEvent.KEYCODE_ENTER);

final EditText edittext = (EditText) findViewById(R.id.edittext);
edittext.setOnKeyListener(new OnKeyListener() {
    public boolean onKey(View v, int keyCode, KeyEvent event) {
        // If the event is a key-down event on the "enter" button
        if ((event.getAction() == KeyEvent.ACTION_DOWN) &&
            (keyCode == KeyEvent.KEYCODE_ENTER)) {
          // Perform action on key press
          Toast.makeText(HelloFormStuff.this, edittext.getText(), Toast.LENGTH_SHORT).show();
          return true;
        }
        return false;
    }
});