Will smoking cause infections in your lungs?

Does increase risk. Smoking increases the risk of pneumonia (lung infection). It also is a strong contributor to COPD (emphysema/chronic bronchitis) which increases the risk of serious complications of pneunonia.
Yes. Smokers are more susceptible to viral and bacterial infections, including colds, bronchitis, pneumonia, lung abscess and sinus infections. You are obviously concerned about it, and this would be a good time to look into smoking cessation programs.