Import new orders (and customers) into database

-- HikaShop version -- : 2.3.5
-- Joomla version -- : 3.2.4
-- PHP version -- : 5.4.32

I have a site online and a rebuilt version of the site in offline dev server. The offline work took way longer that what I anticapated which means the offline site is now out of date with respect to orders and customers. Would it be possible to export (using phpmyadmin) the new customers and orders from the online site and import into the offline site?

Yes. You'll have to export/import the tables #__users #__user_usergroup_map #__hikashop_user #__hikashop_order #__hikashop_address #__hikashop_order_product #__hikashop_history from your online website to your offline website via phpmyadmin export/import tool.