Large Language Models (LLMs) have emerged as transformative, powerful tools for processing and acting on unstructured financial data. However, existing surveys suffer from methodological fragmentation, evaluation inconsistency, and application disconnect. This hinders the transition of research from academia to real-life applications in financial institutions. To address these gaps, we (1) introduce a unified taxonomy organizing approaches by computational complexity, (2) propose a three-stage evaluation framework, and (3) examine LLM deployment approaches suited to specific operational contexts. Furthermore, we identify key challenges including validation frameworks, data contamination, and operational compliance that need to be further investigated.