1. get a little step stool or bucket or something. it helps to be able to put 1 leg up at a time for a while, bend the knee a bit, alternate as you see fit.
2. Yes, I sit for probably 15 minutes or so every couple hours. i got a really high saddle seat chair that I like. goes up to 36" IIRC. You can see it in the pic below. Just make sure to get the highest one you can, and verify it will be high enough before you purchase.