The catch with measuring lifespan of intelligent life or more accurately technological life (the measure of intelligence is rapidly changing at this time but the measure of use of technology remains pretty clear) is bound to two things, firstly what really drives the evolutionary advantage of technology bound life and the other, the lifespan of the technology bound life.
It would seem the biggest driver for technology bound life is repeated frequent and fairly rapid climate change driven by what ever mechanism that provides the advantage for the adaptability of social intelligence over more physical individual biological evolution, so for us repeated ice ages only over tens of thousands of years for a couple of millions years. So the mind can more readily adapt to climate change ie fire, clothing, dwellings than the body. Catch with that is while it will drive biological evolution of the mind it can cripple the development of civilisation by basically repeatedly crushing them with climatic change, floods, droughts, glaciers, storms.
Increasing life span will drive increasing social stability, no longer just say tens of years but thousands of years, just think of the political stability where not just your parents are socio politically active but your great, great ,great etc. grand parents are socio politically active. Think of how those people who lived through the great depression would govern today. Also consider how that kind of lifespan intersects with the vagaries of planets, storms, earthquakes even simple wear and tear of dwellings. Face it for very longed lived sentient technological life, the stability of space borne life is very compelling, so no need to attempt to populate the entire galaxy and the home world becomes more of an theme park for early social evolution.
So what would we see of them, absolutely nothing they did not specifically want us to. Now if they treat their own world like a theme park for early social evolution, how would they treat our world and our primitive society, keeping in mind how many people find something like Meerkat Manor http://www.meerkatmanor.co.uk/ appealing now think of it with cranky short haired crested rock throwing apes and how much more fun and interesting that would be, especially in the shift from throwing rocks at each other to throwing nuclear weapons at each other. That at the positively charming delusion that the whole galaxy is theirs and theirs alone and they will be able to own and control it all. All of it, will be theirs and only theirs and they will bend it too their will, well, at least the psychopathic ones but they currently tend to drag the rest along with them, most often by force.