Bookmarks export and data privacy
Look at Menu/File/Export Bookmarks. If your installation doesn't have this, then update to the most recent snapshot here: https://vivaldi.net/ and then it will.
Vivaldi only collects anonymous user data such as what platform the browser is being used on, and what features are activated/used.
Menu/Help/About tells you all about the browser's guts.
Jon, the founder, has said that he has the resources to go for a long time without making a profit. The revenue model is to make money from search provider deals, etc.
To know where the browser is going, read the blogs and forums and the many, many news articles featuring interviews with Jon.
To report bugs, go to https://vivaldi.com/bugreport.html
Also, a couple of the default search engine links that come with the browser as installed (Blink, Yahoo) are not allowed to be included in the revenue models of browsers unless the browser makers use links which redirect searches through an Israeli company that makes its money by, among other things, capturing your searches and selling your eyeballs to advertisers based on these searches.
However, if you delete these two default searches and then re-add the search engines directly to your search menu, then these redirect links no longer exist. (Vivaldi also no longer gets revenue from your Bing or Yahoo searches, but your searches are more private).
This is something that has been discussed on the forums.