Hi Ido

To answer your questions:

1) This is not yet supported fully, however there is a workaround possible until implement this as a feature.

First, under the general tab of your search for you must select the relevant options under “detect defaults from current page” – this will auto fill form elements based on the current page.

The second stage, is you need to add the the category field to the search form, but you can then hide it with CSS, this will achieve the effect you want.

Just to note, you should not be using “categories” for both your fields – please see the notes here and make sure you are using custom taxonomies, or I guess you could be using category & tag fields: http://www.designsandcode.com/documentation/search-filter-pro/getting-started/adding-new-fields/#Note_Some_Restrictions

2) This sounds like some kind of JS issue.

If you have followed the above and its still not working then please provide a link and I will take a look.

Thanks