As for the pain-not so much. I can certainly feel it but it is tolerable. Truthfully, I walk with the aircast on, which of course makes my right leg higher than my left, which leaves me with more of a sore lower back than anything. But I'll take it not to have to use those silly crutches.
As for the blood flow issue, the short answer is yes and no. The swelling may impair the blood flow a little, but gravity does wonders and just the act of standing will increase the flow to your lower leg. Lying down only serves to keep blood flow stagnant down there, also increasing risk for blood clots. Keep you toes awigglin! And the act of walking will promote bone growth-it detects an area of weakness and attempts to rectify it. This is all in theory, however. unfortunately, it doesn't work on everyone, leading to need for bone grafts, etc. Have I rambled enough yet?

Happy speedy healing-M.