A think there will be life on other planets and my reason is a bit lame and by no means scientific..
A just think the sheer volume of the universe must make some planets suitable for life, not sure what kinda life or if that life is or isn't as evolved as ours but the odds would favour life imo.
A think they will have the same problem as us and that's how to travel such vast distances, if they could am sure we would know about it so a don't believe they have visited earth at anytime..

Its only recently ave got ma head around at just how big the universe is,, its taken me 40 yrs..