Filters and custom fields between categories

-- HikaShop version -- : 4.4.2
-- Joomla version -- : 3.9.26
-- PHP version -- : 7.3
-- Browser(s) name and version -- : Chrome 91.0.4472.77

I need some help please, on how to use custom fields and filters between different categories.

Lets say I have 2 categories. Category A and category B.

1) Lets say I want to have a custom field called "color". It's a custom field and not a characteristic because the user does not select it. So I create a custom field with type checkbox, because a product may have two colors at the same time. Correct?

2) Category A products and category B products, have different values of colors (some are common). Do I create one custom field with all the possible values or do I create 2 custom fields, 1 for Category A colors and 1 for Category B colors?

3) If I want to use color filter, do I create 1 filter or 2? I would guess 2 filters, one for each category, because I don't want to have the colors of the other category displayed in the filter. Does this mean that I also need 2 custom fields? Now the custom field color may also be used in google products xml, shouldn't it be universal? I.e. have one custom field color for all categories?? But then how do I display the values of colors of each category in its filter?

4) Inside the details of the checkbox color filter, on the right side, it says: custom field (have chosen color) and below that, it says "Values". Is this to enter which values I want to be shown? Because this could be a solution to have ONE custom field BUT 2 filters. However, when I enter a value there and hit Save, the value disappears. Have tried with Defined limits on and off. Same thing.

Please advise,

Thank you in advance.

ok. All is clear now! Thank you!