Companies provide a list of their subsidiaries in their 10-K report in Item 1 - Business. A more complete list that includes joint ventures and other corporate relationships is found in this database:
What can you expect to find on the company's website that will help with your analysis?
The company's public relations staff will make periodic announcements regarding key corporate events.
Companies often schedule conference calls to discuss their quarterly earnings and to report on important transactions like a merger or acquisition or change of management. Large institutional investors and financial analysts listen in to the webcast and can ask questions. Transcripts are often provided.
Transcripts of many earnings calls are free at the website Seeking Alpha.
Many companies post transcripts, PPTs or webcasts of management presentations at various investor events. These can be bank-sponsored Conferences that focus on various industry sectors or a company sponsored Analyst Meeting.