Hikashop used for social shopping?

1. Maximum number ? You mean a maximum number of items for each order per products ? There is actually such option already when you edit your products in hikashop.
2. You can setup normal countdown modules and display them in your product description using the loadposition plugin of joomla: extensions.joomla.org/extensions/calenda...nts/events/countdown
docs.joomla.org/How_do_you_put_a_module_inside_an_article%3F
3. Likewise, you can use normal joomla image rotators and include them in your product descriptions using the loadposition plugin of joomla:
extensions.joomla.org/extensions/photos-...ges/images-slideshow
docs.joomla.org/How_do_you_put_a_module_inside_an_article%3F
4. I'm not sure I understand your point. Could you explain more what you want to achieve ?
5. You can set discounts via the menu System->Discounts. With our commercial versions, you can limit your discounts to one product or to a category of products. You can also have several categories for each of your products. That way you can build a special category, attach it as a second category to your products and them create a new content module to display a listing of the products in that special category. That's what we did for the featured products module on our demo website.

We would indeed need to add some options to the listing of products so that it doesn't display the products not yet on sale. Then, you could limit the module listing your products to 1 product and order it by max sale start date so that the latest product is displayed on your module.