Hello,
2. If you have a lot of menu items and can’t save changes then you need to increase PHP Max Input Vars. By default it is 1000, try to set 5000 or 8000 for example http://sevenspark.com/wordpress/menu-item-limit
Also, contact your hosting provider support and ask them to increase the following PHP settings:
– post_max_size to 64M;
– upload_max_filesize to 64M.
3. Seems this problem related to your changes in the child theme. Please check it with parent theme.
Also, your parent theme also contains outdated copies of some WooCommerce template files https://prnt.sc/fhbihl, so I recommend export theme settings in Theme Options > Import/Export > Import or Export your theme configuration > Export Options, then activate some default theme, rename legenda folder via FTP and upload new theme archive in wp-admin > themes or theme folder via FTP (without overwriting), and import your theme options (please make it after increasing PHP settings).
If something goes wrong you can simply delete new theme upload and revert back name of your current theme.
Also, don’t forget to create backup of your files and database before any update.
You need check all the changes you’ve made in the child theme. Sorry, but we can’t know what exactly you modified there and such changes are outside the scope of our support.
If you need help with customization WPKraken team will help you, just submit a request.
Yes, you can update WC to 3.0.8 v.
Regards,
Rose Tyler.