Yes these are possible , you would have to edit some lines of code in the file donate-extra.php
add this to one of the lines with <option> in it to make it the default selected value.
<p class="show_onwall" id="wallops"><label for="show_onwall" >'.__('Show on Wall', 'dextra').':</label><br /><select name="item_number"style="margin-left: 0px !important;">
<option value="0:'.$user_ID.'">'.__('Do not show any information','dextra').'</option>
<option value="1:'.$user_ID.'">'.__('Amount, User Details & Comments','dextra').'</option>
<option value="2:'.$user_ID.'">'.__('User Details & Comments Only','dextra').'</option>
</select></p>
So you could make value 2 the default by doing :
<option value="2:'.$user_ID.'" SELECTED>'.__('User Details & Comments Only','dextra').'</option>
also change these lines too :
var WallOps1 = '<?php echo '<p class="show_onwall" id="wallops"><input type="hidden" name="item_number" value="0:'.$user_ID.'" /></p>';?>';
var WallOps2 = '<?php echo '<p class="show_onwall" id="wallops"><label for="show_onwall">'.__('Show on Wall', 'dextra').':</label><br /><select name="item_number" style="margin-left: 0px !important;"><option value="1:'.$user_ID.'">'.__('Amount, User Details & Comments','dextra').'</option><option value="2:'.$user_ID.'">'.__('User Details & Comments Only','dextra').'</option></select></p>';?>';
Remember to set the SELECTED option and change the value for the class show_onwall from 0 to 1 .
this should get you started.
Thanx
Justine