Silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) are key enablers of high-frequency circuits in modern BiCMOS technology. However, their performance is often constrained by conservative reliability guidelines, limiting both DC and RF safe operating areas (SOA) and overall efficiency. This work explores the impact of device layout, BEOL stress engineering, and aging mechanisms on SiGe HBT reliability and breakdown performance. Through a combination of experimental characterization, predictive aging models, and pulsed-mode measurements, we demonstrate how optimized layout techniques and BEOL-induced stress influence RF-SOA, thermal management, and long-term reliability. By bridging device physics and circuit design, this study provides insights into reliability-aware design methodologies that push the boundaries of performance while maintaining long-term device stability.