I can tackle this one. Basically life as far as we know is rather uncommon. We do know the building blocks appear to be ubiquitous for life as we know it. Effectively, bacteria or archaea-like organisms are the most likely to be encountered. Even if the odds are, say, 1 in 100 trillion (modestly), we've had almost limitless 'trials' to get life at any instant over the last 13 billion years or whatever. That's a lot of trials to overcome odds.
Personally, I think the self assembling nature of much of what we are (from amino acids to RNA/DNA and phospholipid bilayers) makes the odds of life starting up rather promising and likely common...especially if you allow for the possibility of life starting off using different building blocks (example: boron based life, versus carbon.)
It seems recently it was demonstrated that bacteria can go from single cell to multi cell within 60 day: http://www.wired.com/wiredscience/2012/01/evolution-of-multicellularity/
This is actually rather promising for the idea of finding multicellular life, as previous thinking was that the step between single and multi celled life assumed it was a major time consuming crap-shoot to accomplish. Turns out, pretty easy with decent pressure.
As for if they will be 'insect' or anything recognizable...I suspect that there may be passing resemblances to some blobby things like sponges but you won't get many familiar recurrent themes like insects. You WILL however see eyes, as even though the vertebrate eye (including, perhaps, the molluscan eye) may have evolved once, arthropods definitely threw down their own multi-lensed eyes. To get something as organized as an insect, though, you'd need a series of adaptations, mutations and pressures to specifically create the groups foundation, which then can expand and etc.
Familiar themes like bones, for example, may not get the opportunity to evolve. Who knows, it is actually rather mind boggling to think of a life form that isn't just created from a series of traits you already know. Even the concept of bipedality, cephalization (organizing a braing in a head or having a head for that matter) and looking remotely humanlike with two eyes, a nose, a mouth, a neck, 2 arms, 2 legs etc...very, very remote.
I'm sure some other posters such as Astrai will come on and give their 2 cents. it's like 4am, so I'm off to my next adventure.