Oh, you poor thing! Yes, absolutely you’re overwhelmed. Parenting at that stage really is best done in groups of two or more. Consider, next time he’s away, arranging a few breakfast dates or early morning outings so that when the baby is in a good mood, a friend can enjoy his company and give you a break. That way when the inevitable cranky afternoon hits, you’ll have some reserves of patience to deal with it.
Total evolutionary advantage. The ones that didn’t get the timing right ended up as some mastadon’s dinner. 
No way, not at 7 weeks. Even 12 weeks, I might agree with you, for short periods of time, but 7 weekers just aren’t able to manipulate or think ahead like that. He might be able to notice that when he cries, he gets picked up, but it’s a long walk from there to planning on crying in order to get picked up. Even ping-pong playing pigeons take longer than 7 weeks to train.
That being said, I agree with **Sarahfeena **that the boy won’t break if he’s left alone to cry for a few minutes, but at this age it won’t teach him not to cry, it will just let his mother catch her breath and empty her bladder. And, of course, better he cry for whatever reason he’s crying than he cry because she’s hurt him out of exhaustion and frustration.
But don’t turn it into a “he’s manipulating you” thing quite yet. They’re on the same team, they just haven’t quite figured out all the plays yet.