This meta post will summarize the selection results and related findings.
Selection results: 5 suggested, 3 selected for bounties. All bounties were opened to reward existing answer, although some questions remain unanswered (#2, #3, #4).
Dec 20: Pros and cons of installing Ubuntu alongside Windows Boot Manager (selected)
Dec 21: Different colors for active/inactive Unity window title bars? (selected)
Dec 26: Is it possible to run Windows 10 UWP apps on Ubuntu?
Dec 29: Can a Raspberry Pi run Ubuntu? (selected)
Question #2 should be highly concerned, as there seems to be no way to make Ubuntu more friendly to colour-blind users. The high contrast themes are "broken" and almost all themes were not designed to differentiate colours for active/inactive window title bars. Bounty, even twice, has failed to get the real answer.
Related findings: Through this meta post, there are few things that may be inferred alongside user experience of myself as the meta original poster.
Meta may not be visited by established users with relatively low reputation points (around 1,500 points and below)--I similarly have started to engage meta only when reaching that range few years ago, and before that I may have visited but never engaged in meta.
Bounty indeed draws attention, but seems hardly effective at encouraging users to post an answer that actually answer the question--bounty instead may be ignored, or tend to receive new duplicate answers that are not any better than existing answers.
The amount of bounty may be downplayed and does not necessarily valued by users--almost all bounties that I had earned over the years worth only 50 points each, which I had engaged only because there were no other answers that satisfy the question and I was willing to invest some time and had the means to write a better answer at the time; otherwise, unanswered questions with bounty given with 50 or 100 points may be often downplayed (not just on Ask Ubuntu but other SE sites that I have engaged).
Getting a good answer is basically finding a good match that fits the question, and bringing discussion on meta--even if that turned out "preaching to the choir" (having the wrong audience) as pointed by a commentator--was the only known way to clarify this matter.
Credits: Thanks to all users who engaged in this meta post.
@karel, the first and the only suggested post besides the original poster
@Fabby, the one provided bounties to 2 suggested posts
@MarkKirby, @user.dz and other commentators
and all annonymous voters (+18/-2)
That is all to share.