Yes -- many families have shifted from single to dual-earner in order to maintain the same standard of living, so the household income charts really understate the decline in individual wages over this period.
Individual wages have risen steadily since 1910, with no gaps. The household income chart is a misleading chart.
This is a log-scale graph, which is what you want in order to compare rates of increase. You can see sort of an inflection point around the early 80s, but I'm not sure if it's significant.
This is a sum of all incomes from all possible sources devided by population.
Incredibly stable since 1960.
And per capita is a simple average, while looking at medians or quintiles gives you a clearer picture. Per capita, a roomful of middle class workers all become billionaires if Bill Gates walks in.