Set up different shops to use the same products

-- HikaShop version -- : 2.6.0
-- Joomla version -- : 3.4.1
-- PHP version -- : 5.3.29
-- Browser(s) name and version -- : Firefox 41.0.2
-- Error-message(debug-mod must be tuned on) -- : Just question

Hello,
could you please tell me if it's possibe to do the following.

1. I need several sites that will use hikashop and they will have the same products. I need to make them using the same tables in database for products in order to change prices easily on all sites and add products to all sites at once. I am thinking of using one Joomla installation and one of extensions for creating multi sites.
Is any other solution for this? I mean is any way to use different Joomla installations and make hikashop using the same tables in database for products (but for products only, not for settings for payment methods, messages that buyer recieves and so on)?

2. In case when I use 1 Joomla installation for all e-shops, I need different settings for payment plugins, for emails (text, email from address, address of the store and so on) that recieves buyer and seller. As I understand, I can use HikaMarket for this goals? Will be possible to do all I mentioned with HikaMarket?

3. I need to send pdf invoices to buyers. I know you have PDF Invoice plugin to do that. But the problem that I need custom layout for each store. So, for example I need to insert logo of the store in pdf invoice. So I will modify php file for pdf layout in order to insert logo of the store. Is it possible to insert different logos if I have different stores? How can I create own pdf plugin layout for every shop?