Each recipe is for one serving, but if you can't finish it, then no worries...save the rest for later. I recommend keeping it sealed tightly in the fridge for no more than 24 hours. It will depend on what ingredients you use and how filling the recipe is that most likely will dictate if you can drink a full serving. Also, it will depend on your daily caloric needs - some people simply need more than others.
For the seeds - just toss those into your cup before Blasting...no need to mill. The milling blade is good for making flours out of seeds and grains.