I have no doubt the developers have this on their "to do" list.
Given the small size of the team and the priority they have to give to "bug fixing", I do not know how long it be before we get to see it in the UI
But now that we have Release 1.0, hopefully a "complete" UI for Settings will not be too far off.
I get the basic idea of your request and am sure something will be done in these areas in the future.
Although I suspect it will be more in line with the current philosophy of having a "Reading Mode".
However, I would take issue with you referring to IE as "Traditional Knowledge"
Even Microsoft have NOT provided these "features" with their IE replacement browser EDGE - although I do not think that is an example of a good usability guide either
1. Look strange, but I don't use use start screen. So you can try to make a link of your Vivaldi exe (even in same folder of the browser) and to add that to taskbar.
2. Vivaldi doesn't use google API. For import you should push vivaldi button > file > import bookmark and settings > and choose your chrome profile
3. Did you check in task manager if all chrome.exe istances are closed? As last choice, you can export html bookmarks from chrome and try to import in Vivaldi (this usually work). Or try to import from chrome to firefox/ie and by ie/firefox to vivaldi if you need other things as passwords/history
4. You can use search engines located in settings and set start page from there