B12 is only B 12, but you can use human B complex of the super B complex tablets crushed in a spoonful of water or in food 1/4 tablet daily. B complex has B 12 and all of the other Bs, thiamine, riboflavin, niacin, B12, and more.
Paper towel is fine to use with chicks. Hopefully, it is just splay leg, but it can be common to have one that never can learn to stand. I recommend using vitamins as well that contain riboflavin.
Yes that looks good. Be sure to have a non-slip area for the chicken to walk on to get their footing. The foot hobble can be awkward at first, and you may have to help them a bit, but most get the hang of it.
I would put some vet wrap or bandaid on the legs to bring them slicer together for about 3-4 days. The standing in a glass can help strengthen the legs for periods, as well. Here is a good link with pictures to tape the legs about 1 1/4 inches apart...