Looking at the first below I'd say, to be on the safe side, the bedhead should show half to three quarters above your tallest pillow. The second photo I believe shows too much bedhead.

Renovating or restoring as many Victorian features as possible .....Should the 3300 section of your hallway have the original cornice, retain/restore, Many Victorian terraces have a bulkhead along the hall with arch and corbels.

Is there a particular reason you want to lower the alfresco height ? If I had to make a choice , I'd almost prefer to go for 2.7 indoors , 3 metre alfresco , because thats where you want that open feeling , the luxury of space and height , moreso in in an alfresco . As far as being noticed , the only time it wouldn't be too noticable ( IMO ) is if the alfresco floor was lower than the house level -- if you step 'outside' through a standard or sliding door , and the roof feels lower , I suspect you would notice it . That , afterall , is why you go for a 3 metre inside height , to feel open and spacious .

What height window and doors are you proposing. If 3 metre ceilings then 2400 doors and windows would look better. This will then add extra cost for window treatments. Also in the kitchen, with a 3 metre ceiling, where would you stop your overhead cabinets, would you have them to the ceiling? Or standard height? I personally would do your pitched ceiling in living area, and 2700mm everywhere else. This will add extra interest with the change of ceiling height. 2700mm are a good height.