PenciDesign replied
Hi,
1/ I think you should create a new page and use Recipe Index to list all your categories you want here.
Check more on this video tutorial ( please watch to the end of this video to understand all ).
2/ You can check options for Custom Sidebar for Homepage, Single & Page via Customize > General Options.
By default, the archive pages will display "Main Sidebar". So, I think if you want to use a different sidebar for your category pages. You can use Custom Sidebar for your Homepage and use "Main Sidebar" for your category page.
And if you want to make your sidebar align to left, please go to Customize > General Options > and check to "Enable Left Sidebar"
Best Regards,
PenciDesign