There is a lot to unpack in this series of questions, and I'm not sure that I can address all of them, but I'll do my best to to point you towards the best evidence on a few of them.

While its true that the the quality of life has definitely improved in democratic areas, is the root of our wellbeing really owed to Democracy or rather Imperialism?

This question is difficult to answer definitively because there's no universally agreed upon definition of "well being" that isn't tied to a particular context or point of view. We have to be careful about how we we judge the past using modern values, since historical societies often operated according to different conceptions of well being that might seem alien to us. Historians call this "presentism," and generally try to avoid making these types of judgements.

Keeping this in mind, we can look at the relationship between measures such as violence and economic growth and regime type using historical data.

With respect to the relationship between democracy and economic growth, the evidence we have is mixed and is still a topic of ongoing debate in economics and political science. Some prior studies have argued that certain forms of authoritarianism outperform democracies economically, though other more recent studies (e.g. [Magee and Doces 2014] (http://onlinelibrary.wiley.com/doi/10.1111/isqu.12143/pdf)) argue that democracies perform better once you correct for the fact that many authoritarian regimes inflate their reported GDP. I personally find the more recent studies more convincing, but the social science on the issue is hardly settled.

Looking beyond the 20th century leaves us with less data, but there is definitely a lot of scholarly literature on a supposed link between democracy and economic development. For example, Delong and Schleifer 1993 use systematic data on urban population growth and regime type to argue that more "absolutist" forms of government inhibited economic growth in some areas of Europe using data from 1050 to 1800. Arguments of this type can be traced back to Adam Smith, who argued that the "tolerable security of property" found in democracies allowed them to economically surpass more absolute forms of monarchy in Europe. The issue is obviously far from settled, however: for example, Delong 1989 compares Adam Smith's argument with Max Weber's argument that a "Protestant Work Ethic" is the cause of high economic growth in Northern Europe.

There is a lot more to be said on this topic, but I have to go for a bit, so I'll end my post here and return with some discussion of your other questions later if no one else answers them.

It sounds to me like you are talking about the phenomenon of Whig history. While I, personally, have not studied enough historiography to offer a detailed opinion, you may take note that many historians do believe there is such a bias.

In terms of concentration of Wealth i can say that over time wealth is becoming more concentrated. A particular example would be Australia with the Gini Co-efficient score rising steadily over time. Granted this is only one metric of many but my economics lecturer re-iterates time and time again, that government + corporation interaction means that over time inequality will rise as corporations seek to raise profits at lower costs.

So while monarchies dont have a monopoly on wealth, it can be argued that corporations have replaced monarchies in terms of wealth conglomeration