2) Google has a Data Loss Prevention API. https://cloud.google.com/dlp/ That requires uploading your sensitive data. Is that a concern for you? Do you know of better/cheaper alternatives?
2) Usually sensitive data is company specific. E.g., my sensitive data was biotech specific (e.g., chemical, enzyme names). How do you prevent leaks of your custom data?
1. Data tagging or classification - identify and tag your sensitive data, then use the tags to control/monitor what happens to it. If done fully and correctly, you only have to worry about the data that matters, not someone's chili recipe or their kid's soccer schedule. The industry term is Crown Jewels, which represents the data that is absolutely critical to your success and would be catastrophic if lost. Secure your CJ, and your biggest risk is mitigated.
2. Egress monitoring - establish tools or processes to monitor what data is leaving your company, where it is going, and how it is getting there. Look for anomalies, abuses, and undesired activities. Perhaps your intellectual property should never be in China.. uploads to 163.com or message attachments to QQ messenger addresses might be concerning.
3. Technical controls - Does your company need USB drive access? If not, block them all from moving data via USB. Does anyone in your organization burn data to CD/DVD media? No? Block it. Turn off the egress vectors that aren't needed at a user/team/site/org level. The most common egress vectors are USB, CD/DVD, Email, Network Upload, Print, and wireless transfer like bluetooth. There are others, but these are the most encompassing. You can do things like block all emails going to personal email domains like gmail or yahoo; limit print amounts to 20 pages per user per day; or block access to all domains/IP's in specific countries or regions on the network.
4. Security Awareness - Employees need to be fully informed about the data protection requirements you have in place, and the related consequences for breaking acceptable use policies. Education and awareness campaigns are key, and probably the most overlooked option available. I personally believe informing employees about real life cases of data loss/theft, whether they are your own or just in your industry, is crucial in making the risk seem more real.
I can't recommend any specific products, but in general I would say look for tools that can give you things like: data tagging, network activity logging, end-point monitoring, anomaly detection, live response, data loss prevention solutions, and/or critical data protection.