Does a talc pleurodesis decrease my breathing in any way?

Just the: Reverse. It's used to prevent pleural fluid from recurring in a malignant pleural effusion.

Generally no: Talc pleurodesis is used to prevent recurrence of air (pneumothorax) or fluid (effusion) in chest cavity. When pneumothorax or effusion occur, they occupy space where lung should be. This prevents the lung from fully expanding. So, pleurodesis is used to improve /maintain lung expansion. Modern thoracic surgeons will use vats (minimally invasive techniques).