Set Magento site to "Production" and optimize

We have a Magento site that we have developed for a client but are having problems setting it to "Production" mode. It generates an error in SSH and log shows: ----------------------------------------------- New version of deployed files: 1510955257 [2017-11-17 21:58:51] [login to view URL]: Cache file with merged layout: LAYOUT_frontend_STORE1_10178900be76e671b170710e96287f8b8f and handles default, cms_index_index, cms_page_view, cms_index_index_id_everything-home-one-column: Please correct the XML data and try again. Element 'css': This element is not expected. Line: 186 [2017-11-17 21:58:51] [login to view URL]: Broken reference: the '[login to view URL]' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:58:51] [login to view URL]: Broken reference: the '[login to view URL]' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:58:51] [login to view URL]: Broken reference: the 'wishlist_sidebar' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:58:51] [login to view URL]: Broken reference: the '[login to view URL]' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:58:51] [login to view URL]: Broken reference: the '[login to view URL]' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:58:51] [login to view URL]: Broken reference: the '[login to view URL]' tries to reorder itself towards 'minicart', but their parents are different: 'header-wrapper-container' and 'header-wrapper' respectively. [2017-11-17 21:59:41] [login to view URL]: Cache file with merged layout: LAYOUT_frontend_STORE1_10e13260053f56644d576f1e487266f9a1 and handles default, checkout_cart_index: Please correct the XML data and try again. Element 'css': This element is not expected. Line: 186 [2017-11-17 21:59:41] [login to view URL]: Broken reference: the '[login to view URL]' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:59:41] [login to view URL]: Broken reference: the '[login to view URL]' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:59:41] [login to view URL]: Broken reference: the 'wishlist_sidebar' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:59:41] [login to view URL]: Broken reference: the 'checkout.cart.item.renderers.gift-card.actions.gift_options' element cannot be added as child to '[login to view URL]', because the latter doesn't exist [2017-11-17 21:59:41] [login to view URL]: Broken reference: the '[login to view URL]' tries to reorder itself towards 'minicart', but their parents are different: 'header-wrapper-container' and 'header-wrapper' respectively. [2017-11-17 21:59:41] [login to view URL]: Broken reference: the 'checkout.cart.item.renderers.gift-card.actions.gift_options' tries to reorder itself towards '', but their parents are different: '[login to view URL]' and '' respectively. ----------------------------------------------------------- We are also having problems with it overloading the server (it's on a dedicated cloud server) so we need a Magento specialist to check to make sure everything is set properly and optimized.