Normal blood pH is about 7.4 in most tissues (it is a bit lower in veins since they carry waste products, which are acidic). To get back to the physiological set point of pH = 7.4, we want to remove the acid from the blood. The major blood buffer system is shown in the following equation: 

As we know, carbon dioxide is one of the major byproducts of respiration, and is considered waste for our bodies. Combined with water and catalyzed by carbonic anhydrase, it is converted into carbonic acid. Carbonic acid is a weak acid and will partially dissociate into hydrogen ions and bicarbonate ions. Thus, overall, carbon dioxide and water yields acid (hydrogen ions). As a result, excess carbon dioxide in the blood will lower the pH.

In order to increase the pH, we must stop this equation from proceeding in the forward direction; thus, (remember Le Chatelier's principle) we must remove carbon dioxide from the left side. This will push the reaction in the reverse direction, quenching hydrogen ions (acid) and removing them from the blood, increasing blood pH back to normal.

Since we want to get rid of excess carbon dioxide, we breathe faster. Oxygen does not have any effect on blood pH. Furthermore, the atmospheric oxygen level (21%) is plenty for our bodies to utilize, as when we exhale there is about 15% oxygen left over, meaning we only use about 25% of the oxygen we breathe (this is why CPR works!).

Surfactant coats each alveolus, and is a detergent that lowers surface tension that prevents the alveolus from collapsing on itself. Also, decreasing surface tension facilitates the diffusion of gasses across the alveolar epithelium.

Cyanosis in the body occurs due a reduced hemoglobin concentration that is at least 6-8 grams of hemoglobin per deciliter of blood lower than the normal hemoglobin range for men and women.

Hemoglobin is what carries oxygen in the blood. The blood then carries this oxygen to various tissues in the body. When hemoglobin is low, oxygen is not delivered fast and efficiently enough to the appropriate tissues of the body, thus turning them visibly blue (cyanosis). 

The man has above normal residual lung volume , as the normal residual volume (RV) for an adult male of average size is 1.2 liters. Causes for such high residual lung volumes in a man can occur from lung diseases, such as emphysema, that cause obstruction of the lungs and trapping of air. 

The partial pressure of carbon dioxide would be the highest in systemic venous blood. This is because the systemic venous blood contains both the carbon dioxide that was in the systemic arterial blood and that which is added to the blood by tissue metabolism as the blood passes through the systemic capillaries.

The normal oxyhemoglobin concentration in mixed systemic venous blood for a person at rest is 75%. Therefore, a person with a oxyhemoglobin concentration of 25% is much below normal.

The total lung capacity (TLC) = IRV (inspiratory reserve volume) + TV (tidal volume) + ERV (expiratory reserve volume) + RV (residual volume).

The total lung capacity (TLC ) is the maximum volume of gas present in the lungs after a maximal inspiration. It includes all of the possible lung volumes.

Alveoli are the terminal point of the respiratory zone and closest to the blood vessels in the lung. Since gas exchange uses diffusion, using alveoli makes sense because they are closer to the blood vessels.

Hemoglobin's primary function is to transport oxygen from the lungs to the myoglobin in the tissues that need oxygen. Oxygen is required for aerobic cellular respiration, so the tissues that have high metabolisms require the most oxygen. The byproducts of metabolic processes include acid, heat, carbon dioxide, and 2,3-bisphosphoglycerate (BPG). It should make sense that the byproducts of metabolism (evidence that oxygen is being used) influence hemoglobin to drop off its oxygen. Remember, if we stabilize the deoxygenated form of hemoglobin, it is less reluctant to drop off its oxygen since the oxygenated form of hemoglobin is always more stable than deoxygenated.

For your reference, 2,3-BPG is an isomer of a glycolytic intermediate that sits in the central cavity of hemoglobin. 2,3-BPG carries a large negative charge, and interacts with the basic (positive) amino acid side chains facing the central cavity of the molecule. When positives and negatives are close together, the molecule is stable.

The main role of surfactant on the alveoli (the lining of the lungs) is to decrease the surface tension of the lungs. Decreasing the surface tension allows more air to enter the lungs, in other words, it increases the compliance of the lungs.