Will taking testosterone reduce my gynecomastia?

No. Excess testosterone (t) is converted into estrogen which then exacerbates gynecomastia (male breasts). So taking t won't help you. Instead, check your estrogen level and block conversion of t into estrogen w/aromatase inhibitor such as anastrazole (prescription breast cancer drug). Of course, diet & exercise help, too! less fat = less gyno. Plastic surgeons can help when all else fails.
No. The development of breast tissue in men is a function of the tissue sensitivity to estrogens, not a low testosterone.
No. Gynecomastia is a diagnosis typically found in men. You should see a surgeon for an examination and evaluation.