This forum is full of thoughts on hoods, including ceiling capture. Some searching would be advantageous to understanding the issues.

Cooking plumes rise and expand. If the capture area is within about 3 ft of the pan, the hood has to extend only several inches beyond than the extent of the potential cooking pans. Nominally, most of the plume is within a cone that has sides sloping at 10 degrees to vertical.

However, the higher the capture area, the larger it has to be to accommodate the expansion. Also, the plume momentum slowly drops, and becomes ever more susceptible to cross drafts and room air motion. Commercial cooking hoods are typically at 7 ft from the floor, and are quite large relative to their cooking zones. At 8 ft they would have to be even larger. At some point, perforated ceilings are used because the plume effluent can drift too far to depend on a hood cavity for capture.

http://www.kitchen-ventilation.co.uk/heydal

Normally in hoods, the baffles are used to collect grease, or more
accurately, the larger end of the grease particle size spectrum. A
register at the ceiling will pass most grease into whatever ducting is
being used. In deliberate ceiling collection systems, means are
provided for grease protection (fire protection). One such method is
intense ultraviolet.

In the range of 30 inches to four feet above the cooking zone, hood capture areas need a flow rate of about 90 CFM/sq. ft. to assure that the captured effluent will remain within the hood (be contained). While this may be relaxed slightly at 5 or more feet, the large size of the capture area required will still require a growing flow rate (with) ceiling height.

On your more prosaic questions: You may use an in-line (axial) blower or an external radial blower, either on the side wall or roof. If a silencer is placed between the blower and the hood, blade tip turbulence and duct wall turbulence from the portion of the duct towards the blower will be reduced.

I don't own the Miele so I can't comment on its potential other limitations or its advantages.

Thank you. I did search after I posted and found loads of info.