Re: How much do I need to freeze if EP?
I don't EP but I am away from DD for 12+ hours 4 days a week. I pumped every 3 hours until DD was 3.5 months old (so about 5 times in that 12 hour day as I pumped on my way home too). At that point I dropped one pump, then at 4 months I dropped a second pump. DD is currently 6 months old and I pump at 7 AM, 1 PM, and 6 PM on work days. My supply didn't drop with the dropped pumps, I just pumped more per session. AF came back when I decreased pumps though and now I do notice that my supply dips by a few ounces a day right before I ovulate up through AF (but between AF and "o-day" my supply is as high as it ever was). So I suspect that once your supply is well established you can start lengthening the time between pumps (probably more ideal) or dropping one pump at a time. I think a lot of EPers can get down to 3 or 4 pumps per day once their babies get a bit older.
As to how much you need to freeze, I guess that depends on how much your baby takes on a daily basis. My DD's consumption has remained pretty stable since I went back to work full-time at 3 months other than a few little blips when she had a growth spurt or major schedule change. So once you're comfortable that your baby's consumption has stablized, you need to figure out how much per day multiplied by the number of days you want to exclusively feed stored milk. Personally I'd add an extra 10% or more to make sure you have plenty.