Limiting frontal area=drag is a design goal. Wide fuselages create a lot of unused frontal area on the cargo deck as well as above the ceiling, like on the 777. Boeing tried to turn it into a added value, but the market told Boeing they don't like the sky loft ideas.
The ecoliner concept uses the lower part of the 777 standarizing cargo hold, wing torsion box etc
As you can see the upperdeck of the ecoliner has a diffrent shape then the 747 upperdeck, making room for serious luggage stowage and use as 6 abreast economy a serious alternative, unlike the 747.
A ten abreast maindeck is not required for the envisaged market segment, below the A380, 370-500 seats. It can be done like on the 777, but is not standard for mainline long haul services.
On the APTU air inlets : those are retractable and melt into the fusealge during cruise. Dependent on size I can see about 4 of them. I think that is also what Boeing considered for the 777 hgw in the nineties.