On the Frontend Search settings if you exclude the categories, they will be only excluded from the settings – not from the actual search.
See the documentation: http://wpdreams.gitbooks.io/ajax-search-pro-documentation/content/frontend_search_settings.html
This section only affects the frontend settings filter – to actually exlude categories and include post types go to the Advanced Options panel and to the General options panel.
If you want to override the default wordpress result list, then you need to enable it. On the General Options -> Behavior panel, enable the “Override the default WordPress search results page?” option.
To change the vertical results size, you need to change the Results box viewport (in item numbers) option on General Options -> Behavior panel.Best,
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