The screenshots didn't came through, but I think I understand your questions.
1. I believe so. You can create a search instance to only search for attachments and nothing else, and use that search shortcode on a page where you need it.
2. If you mean the live results on a different location than on the bottom of the search bar (floating results), then you can use the results shortcode for that: https://wpdreams.gitbooks.io/ajax-search-pro-documentation/content/getting_started/custom_result_box_position.html
3. The plugin can only filter the live results within it's own results container unfortunately. Each theme is very different in terms of archive pages and the output method, I was not able to overcome that obsticle to have an in-place template filter feature.Best,
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