Those lines say "Unused" in SimPe, the word "Unused" comes from within
SimPE so the game version is irrelevant.
I've never looked into the Downtown, Holiday or even Community sort values, I just copy the values from any item that's already in the correct catalogue locations.
I'm quite sure it'd be OK for something to be in more than one category but.. It must be in the most appropriate category or we'll have a hard time finding it. It can be tough enough finding what we want without having to sort through stuff that's also in inappropriate categories.
The catalogue ratings are just for the catalogue dialogue, they can be as high as you like but you would only be fooling yourself by giving them a higher rating than they should be, typically a value of 10 is the highest you'd see.
The skill flags have the following:
+ Cooking Skill Flag 1
+ Mechanical Skill Flag 2
+ Logic Skill Flag 4
+ Body Skill Flag 8
+ Creativity Skill Flag 10
+ Charisma Skill Flag 20
+ Study Skill Flag 40
+ Cleaning Skill Flag 80
Also, not used as much as they could be the 'Catalogue Use Flags' have the following:
Group Activity Use Flag 4
Can only be used by Children Use Flag 2
Can only be used by Adults Use Flag 1
Can only be used by Teens Use Flag 8
Can only be used by Elders Use Flag 10
Can only be used by Toddlers Use Flag 20