I imported a WordPress blog that stored my records but lost my Groups, Tags, and custom fields. I've got a backup from the MySQL database that consists of that info. What type of MySQL query should i fetch/export everything metadata from the backup db, after which import it into my brand new one?

I'd copy the wordpress_term_associations, wordpress_term_taxonomy, wordpress_terms, and wordpress_links tables. Most likely wordpress_postmeta too. Surveys are within the wordpress_coments and wordpress_commentmeta tables. You can easily export these tables within their whole and import the information to your new database.

I believe generally, if copying one site to a different, you are able to copy all tables except the wordpress_options table. This is when the website configuration is saved, which may cause problems when moved in one site to a different.