Hi,
2. You have to put these options into the same category and unpublish this category or in the menu select a category different than the previously created one. (and the created category must not be a children of the selectd one.)
3. I think that you have to use the variants, and change the value of the option "Characteristics selection method" in Configuraiton > Main > Product.
Else when using the options, you will have to display all the options instead of a dropdown, and it require custom code, there is no default options for that.