Hi VinceV, I'll try to answer your questions. The Dremel brand and Bosch Tools are siblings of Robert Bosch Tool Corporation. However, the two brands are run as two separate business units. Each has their own president and staff and budgets. Next, I'll address your questions 1 and 2 below.
1) There are more divisions. Too many to list here. Inside North America there are divisions that fall broadly under automotive, home, and industry, groups. The Power Tool division falls under the Indusry and Trade group.
2. Largely, the tools made under the Bosch name are completely diferent from the tools made under the Dremel name therefore the parts would be completely different. If you have a specific part where you think there may be compatibility with a Dremel part, let me know and I'll see if I can get you an answer.