Software vulnerabilities are prevalent in software systems and the unresolved vulnerable code may cause system failures or serious data breaches. To enhance security and prevent potential cyberattacks on software systems, it is critical to (1) early detect vulnerable code, (2) identify its vulnerability type, and (3) suggest corresponding repairs. Recently, deep learning-based approaches have been proposed to predict those tasks based on source code. In particular, software vulnerability prediction (SVP) detects vulnerable source code; software vulnerability classification (SVC) identifies vulnerability types to explain detected vulnerable programs; neural machine translation (NMT)-based automated vulnerability repair (AVR) generates patches to repair detected vulnerable programs. However, existing SVPs require much effort to inspect their coarse-grained predictions; SVCs encounter an unresolved data imbalance issue; AVRs are still inaccurate. I hypothesize that by addressing the limitations of existing SVPs, SVCs and AVRs, we can improve the accuracy and effectiveness of DL-based approaches for the aforementioned three prediction tasks. To test this hypothesis, I will propose (1) a finer-grained SVP approach that can point out vulnerabilities at the line level; (2) an SVC approach that mitigates the data imbalance issue; (3) NMT-based AVR approaches to address limitations of previous NMT-based approaches. Finally, I propose integrating these novel approaches into an open-source software security framework to promote the adoption of the DL-powered security tool in the industry.