Surround speakers for most systems can be mounted anywhere from about sitting ear level to above standing head height depending on your room / requirements (using speakers from the Firesprite (bookshelf) or Fusion (flat panel range). Or stand mounted, or small floorstanders could be used such as from the Sentinel range.
Subwoofer placement is very flexible.
Bookshelf speakers can also be used as fronts.
You can upgrade any system to Dolby Atmos, Auro 3d or DTS:X either now or at any time in the future simply by adding additional speakers.
You can either install them yourself or get any local electrician to install them according to this placement guide
Dolby Atmos Placement Guide
For DTS:X systems the same configuration as the Atmos systems is a good place to start. You have the flexibility to use either ceiling speakers or high wall mounted speakers as the high level (similar to the Auro 3d systems). The suggested placement for high wall speakers is above the front speakers and in line with where ceiling speakers would be (as in the Atmos/DTS:X systems shown). Placement with DTS:X is very flexible though with the option to place or add additional speakers in many different locations.