Hahahaha, actually the rule 2 also applies. It appears that this topic belongs to the Suggestion box sub-forum. 😃
Please take my joke easy @lukteper. 🙂
Tabs Stacking or tab grouping
It looks like there are a handful of extensions to create and manage tab groups, you could take a look in Opera's extension catalog, Chrome Extensions Web Store (there are some like Opera's left/right positioned tab bar / Windows panel Sidewise Tree Style Tabs - to install Chrome extensions in Opera the easy way: https://addons.opera.com/extensions/details/download-chrome-extension-9/
am I even supposed to do with stash? Where is the organized folders of content Ive spent years on creating?
The purpose of Stash is to index the content (text) of pages you save there so you can use the search field to filter them easily, if you want folders you can have them in the Speed Dial (1 level deep) and more sub-folder levels in the bookmarks bar you can enable in the settings. To import your bookmarks it'll depend from where you want to do this, try searching the forums as there are plenty of topics with instructions or via a search engine "import bookmarks from XXX site:forums.opera.com".