I'm so sorry Iris has escaped, I agree with Cathy that chewing is a natural instinct females have when coming into condition, which sounds like that was what was happening. They tend to get more moody, more aggressive and very interested in exploring and chewing at things.
I agree with advice above, I'm hoping you will find her. Poor Icarus, he probably is confused as to why his friend has gone and is a little more apprehensive of you without her there.
I do hope she returns, but in the case that she doesn't, I would agree that getting him a friend is the best option.
If he is young enough (What I mean by that is he isn't an 11 or 12 year old budgie who is grumpy and set in his ways) then I would get him a younger budgie for a friend. If you aren't intending to breed, a young male is always the best because males tend to form strong bonds of friendship. Of course, a female works too, but then you have the risk of eggs/babies.
If you do decide to give him a friend, it's important you quarantine him/her for 5-6 weeks in a separate cage in a separate room to prevent the spread of diseases, after that you can introduce them in a "neutral" room and have them share some millet and playstand/play area so that they get to know each other. Once they're together, some squabbling is normal at first, to limit this make sure there's two of everything, even if there wasn't when Iris was with him.
I hope this helps and please keep us posted, I can't imagine what you're going through right now