Short answers, pulled from the story.
The group assigned the name Old Faithful to this specific cone geyser on the afternoon of the 18th of September 1870. This event marked the first time a geyser in Yellowstone National Park received a historical name.
In the early days of the park visitors and staff often used Old Faithful as a laundry site. An 1883 Yellowstone guidebook detailed how people utilized the site for practical purposes before it became part of the Old Faithful Historic District.
Since 2000 the average interval has slowly increased to 90 minutes apart. The time between eruptions shows a bimodal distribution with mean intervals of either 65 or 91 minutes depending on the length of the prior eruption.
Between 1983 and 1994 some video probes reached depths of 1,000 feet to observe the conduit formation inside the earth. Temperature measurements of the water at this depth were 470 degrees Fahrenheit matching data collected in 1942.
After the Borah Peak earthquake in central Idaho in October 1983 the eruption intervals of Old Faithful were noticeably lengthened. Earthquakes affecting subterranean water levels shifted how often the geyser erupts while making earlier mathematical relationships inaccurate over time.