There's an evolutionary theory that grandmothers are a contributing factor in the survival of offspring and could be a cause of humans longevity. If there's any truth in it, male lifespan would have likely also increased (over many many generations, in the distant past), but not as much as female lifespans - the selected trait.
I think there are breathing tricks to try and get rid of stitch - such as if it's on the left, breathe out hard every time your left foot hits the ground, and vice versa if it's on the right. (Possibly the other way round - sorry!) Breathing out hard seems to be key, anyway.
You've got a few days yet, right? So rest, drink lots of fluid, take lots of vit C, zinc, etc. (I know there's conflicting evidence on whether there's any point to taking vit C/zinc when you have a cold but there are times when it's worth a try) and with a bit of luck you should be feeling better by Monday. I hope so anyway - good luck!
I did Berlin last year and LOVED it. Loads of support, great city. Filled up very quickly this year so you do have to be quick to get in. Will be doing Amsterdam this year, and am thinking about the French Riviera marathon for 2014.
I did my first marathon last September and found running 26.2 M on the day much easier than running 20 M in training so be reassured - you'll get round. As well as the atmosphere and support to help you out on the day, you'll be fully rested, hydrated and carb-loaded from the taper. Good luck and enjoy your first marathon!