Discussion/review - own type or section?

It is a "Content plugin". So, it works on J! core content articles.

Actually, it works in all "areas", which are able to run content plugins. i.e. Cobalt HTML field.

Usually, you need to enter the respective shortcut syntax into a J! article or Cobalt HTML field etc.

(You can see the usage in Sergey's Cobalt 7 tutorial video)

HeadsUp: Hence the plugin parameter "In Categories"!

Here you can enter multiple J! category ID#'s. Seperated by comma, like so: 5,8,12

This automates the plugin call for ALL articles in those categories!

No typing of plugin syntax ;-)

Do I have to create a separate type and section for this?

Yes. (If you don't have a special storage location)

You might store the reviews in a seperate Cobalt section,

or in a section which already include other types. For this purpose you can force storage into a sub-category. Hence the "Default Category" parameter. You have to enter the respective cobalt category ID#.

Do I have to create a separate type and section for this?

Does this mean it doesn't work on cobalt articles?

Not automatically, like for J! categories.

But you can enter and use the content plugin syntax in all Cobalt areas, that run content plugins i.e.: HTML field, TextArea, Category descriptions.

Do I have to create a separate type...

The type represents your "review form". Since it is not a pre-defined comment field... you can do crazy stuff: Create and use as many different fields as you want.