For the hood, it sounds like the two wrong sides should be joined together to make a ridge or welt along the neck edge. If you mark the row where the pattern gives these instructions, you can do this when you're finished with the hood.
For the sleeves, it seems like the G part of the sleeve cap is sewn to the perpendicular line to its left and then one side of the saddle is sewn to the front of sweater and the other side is sewn to the back of the sweater. The sleeve is set into the armhole as usual from one side of the double pointed arrow to the other. I usually pin all this together and even baste it to make sure everything sits right.
I can't tell where the "live sts" that the pattern talks about are located and that may help you with attaching the G part of the pattern.
Is there a link to this pattern, or a name for the sweater? it might help to look at a picture.