RE: It's been a year now
-- Opening links in a new tab with a mouse gesture
For this I use long time middle mouse button press. Works almost everywhere, also in other browsers. Except MS Sharepoint portal as I know.
-- Give us the possibility to change tab switch order so it will cycle through the latest active tabs instead of just cycling through them in order.
Use this link for Experiments - Tab Cycling -
"opera://flags/#activation-order-tab-cycling". Set it to Enabled
( Why site doesn't allow to use Opera's own Links? )
-- Quickly editing site-preferences by right clicking on the website and choosing "Edit site preferences"
Even when I'm not protagonist to use extensions for every simple functionality (that can be in core), you can use as for now as workaround this extension Site-specific Preferences.