Re your question "with myself" i.e. alone.
Having completed the task, I was able to leave. = Because I had finished the task, I was free to go.
Such a locution implies that "I" had done the task alone. If you wanted to involve others, it would be:
Because we had completed the task, I was free to go. or Because we had completed the task, we were free to go.
There is no way to express that idea in the initial clause when it begins "Having completed" because there is no way of expressing differences in number with "having completed". The number will be in the second, independent clause:
Having completed the task, I was free to go.
Having completed the task, he was free to go.
Having completed the task, they were free to go.
Prosecuting attorney:
Colonel Mustard, having completed the task, did you leave the premises immediately? Or did you stick around and murder Professor Plum in the living room with the candelabra?
HAVING HAD...
I had a scar on my belly, having had my appendix removed as a child.
You cannot remove your own appendix. So you had it removed. That is, you took action to have another person remove it.
I will have the house painted before we put it up for sale.
means that you will hire someone to paint the house for you.
After having had the house painted, we put it up for sale but then decided to stay.
After having the house painted, we put it up for sale.
The phrasal verb get over means recover from. It's often used in the context of overcoming illness, injury, or a painful experience, but I like the way this Oxford dictionary defines it:
get over (phrasal verb) recover from (an ailment or an upsetting or startling experience): ‘the trip will help him get over Sal’s death’
In this case, the person is simply surprised by his old friend's face. We don't know why (context doesn't say), but we can make some guesses:
I can't get over the way your face looks – you look so young! (surprise)
I can't get over the way your face looks – your wife's death must have been hard on you. (empathy)
I can't get over the way your face looks – where is that face painting booth? (laughter)
Any of those three are possible, but I suspect it would be the first. It mirrors what one person wrote in an advertisement for a nutrition product:
Recently I was at a gathering, and was in the company of a man I'd worked with in 2003 and 2004.
I noticed he kept watching me. Finally I went over to him, extended my hand and introduced myself.
He said, “I know who you are, I just can’t get over how you look. You look twenty years younger.”
Best Answer
Everything here is referring to the list of things that the person wanted to get done. If I had five things on my list, and I completed all five tasks, then I would have completed everything on my list of tasks... so therefore I got everything done.
In this case, where usually the kids take up a lot of time and keep the list of tasks from being completed, the person still has a problem finding enough time to complete the list of tasks even when the kids are gone, so therefore everything on the list does not get done.