Yes it can help a lot. I got some tried it on myself and it helped. I tried it because the vet gives the animals a B vit shot when they don't fee well to help perk them up.
Yes, vitamin b helps to prevent fatique and anemia, this is especially true with vitamins b6 and b12.
Yes, my mom swears by it and uses a sublingual form that disolves under the tongue
Yes and no. Vitamin B12 has been known to be used to treat fatigue, but only in people who are B12 deficient.