Dear Ricardo Fernandes,
About the strict standards, due to our template was developed long time ago, it is compatible with old version of PHP. But now it is new PHP version, so it have some warnings. So, you could hidden the warnings first, we will update the template as soon as possible, and announce for you.
And about the warning: Permission denied in /usr/share/nginx/html/loja/libraries/joomla/filesystem/file.php, this is due to its decentralization. You could fix by change file permission to 755.
Thanks & regards!