These four requirments comes right of the box with wordpress. You don’t need any extra plugin for that.
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Any user can register – Go to
General settings
page and enableAnyone can register
option by checking checkbox available next to it. -
They can post product – Assign them a role of author so that they can publish posts, do comments, upload media etc.
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Users can comments – By default anyone can comment on posts (products), From ‘Discussion Settings’ menu you can configure it such a way that only registered users can do comments.
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Users can view all products – post author can edit their posts, comment on their post etc.
For Ratings – Take a look at WordPress Plugin Directory, You’ll find plenty of good rating plugins there.