What, if anything, do I do to the rhubarb plant for winter? Do I cut back the existing leaves and stalks or leave them?
Rhubarb is native to Siberia. It needs absolutely no winterizing and actually performs better when it gets a healthy does of cold weather.
Should rhubarb stalks be red or green before harvesting?
It depends on the variety. Some varieties should be red when harvested, while others should be harvested when green because the stalks never turn red. If you have a red variety, wait until the stalks are red to harvest.
Should you cut the blossom stem off? Mine has grown to about 12 inches tall.
I would cut it off, unless you want the seeds. Letting it produce seeds just diverts energy from producing leaves and stems and does not help.
Are the leaves ok to put in the compost bin?
Yes, it is ok to put rhubarb leaves in the compost bin.
Is it ok to use mulch around the new planted rhubarb plants (light cover)?
Yes, this will actually help them retain water and grow better.
When rhubarb goes to seed, should you cut off the seed pod and continue to harvest rhubarb or should the entire seed stalk be pulled from the plant?
You can just cut the pod off. You can continue to harvest the stalks.
I live in Georgia where the summers are hot and muggy. I understand that Rhubarb does not do well in this area. I've ordered a couple plants in the hopes that I can put them in pots and bring them indoors if it gets too hot in the summer. How well is this likely to work? Should I just buy generic potting soil, or should I buy some and add some peat moss or something to enhance the drainage? Any other tips for planting Rhubarb in a pot?
Your biggest issue will be getting enough light for the plant when you bring it indoors. You may need to use supplemental light. You can also just try moving it to a shady part of the yard if it gets too warm.
Plain potting soil will work fine, but make sure the pot has drainage holes.