I agree you have several things going on with your blueberries.

1. The holes in the leaves and the leaves that have the transparent brown sections in middle have been fed on by leaf miners. They may be responsible for some of the black bits on the other leaves also. On a couple leaves there is something small and brown, maybe an aphid?  For now I would manually remove any insects and consider an insecticide treatment post harvest if needed.

2. Some of the leaf discoloration seems to indicate nutrient deficiency. The reddening leaves may indicate Magnesium deficiency. You can apply Epsom Salt at a rate of 3 ounces per plant to correct for this.

3. There may be some fungal disease also. In Georgia, I would recommend Serenade Max or Captan to be applied for the leaf disease.

 Are the leaves with the discolorations from this year's growing season or last years? If they are last year's leaves, I wouldn't be too concerned. If the discolored leaves are from this year, you may need to change your fertilization program some. Fertilize products that are recommended for Azaleas will typically work well for Blueberry plants