since the name of the file is a string, it will need to be enclosed in single quotes in the onclick event:
document.getElementById('borrarar').value='<?php echo($row_WADAbanco['Logotipo']); ?>'
you can use the files created by the wizard in dynamic plugins, there is no need to hand code them.
to build a results page that includes the search form, go to the Data Assist Create pages wizard, and go to the Manage pages tab. Click the Plus button and select Results page to have a results page created, in the results page settings, click the plus button to select the columns to include in the results layout and click ok.
click the plus button again and select Search, in the search page settings, select the option to include the Search form on the results page.
I have logged the issue with png backgrounds. can you provide some more details though:
are you resizing the image? Using Images only? are you converting the Image types? Some additional details on the upload settings you are suing would help us track the issue down.