I think you have problems. Those room ratios are not good and that room will always sound suboptimal what ever you do. I don't know what your house plans are, but your big problem is that the room is far too short to be optimal. You need about 10 more feet. I would not use a drop ceiling. Having the room rigid is very important.
The other problem with the room being too short is that you will not have the room to get enough seating to justify the work and expense.
I have just been through this and will post my links. But rigidity is very important. This is an ICF home which is a good start. For acoustic reasons sound insulation was placed behind all walls and under the floor, and extensive insulation over the ceiling.
This room sounds excellent and does not need any room equalization at all. You definitely hear the original acoustic and not the room predominantly.
The next is to engineer the room so all cabling can be easily changed. That means extensive use of conduit, lots of it. Also, it is strongly recommended to make that room the nerve center of IT and all AV distribution throughout the house.
Next you have to think about power protection in a project like that. That starts with whole house surge protection.
Next in new construction, and this is very, very important. You need to carefully need to plan not only your theater ground plane, but do that in conjunction of the planning of the ground plane for the whole house. In addition separating lighting circuits and appropriate dimmer selection is crucial in these days of LED light bulbs and SCR dimmers. Otherwise you will put in a lot of time and effort and end up with a noisy buzzing theater and not be able to do anything about it.
I agree ceiling speakers are a problem, and would strongly recommend a full ranger, like those from Mark Audio. You will need to build back boxes.
Build thread.
AV room.
Great room system.
Family room system.
Hopefully this will give you some ideas. You need to pick your electrician carefully. But remember you have to really understand the issues and take total control. It is highly unlikely the electrician will understand the issues involved and you can bet serious mistakes will be made without your guidance.
If it sounds complicated, that is because it is. It is what it takes however to build a first class theater.