I can answer the first part. If your budget can afford it, go with the 3 appliances. The cooktop can be used as a light work surface if space is tight (with proper protection)

The best reason to separate the cooktop and oven is to keep the cook from overheating. With induction, there is very little heat escaping from the surface so you stay much cooler so why put something hot under the cook surface?

The other reason is ergonomics so you don't need to do gymnastics to use the oven. Even raising the oven 10-20 inches off the floor makes baking so much easier

I will defer to others on the speed oven other than 2 comments(maybe 3)
1. You can mix and match appliances. I have a wolf and an advantium.
2. You can use a setting for something other than what it is designed to cook. I frequently choose a speed setting for a similar type of food (but also understand the custom settings but don't always take the time to create a new program. If Bosch allows custom settings, just figure out the basics and the world is your. I do create custom settings frequently on the advantium in addition to using what is in the programs
3. Side opening woud be nice especially if you are putting it above a regular oven. By design, our advantium is at max height. When we sell our house in 18-20 years, a shorter person would not like the heighr.

a2gemini, Thanks for your reply