You may take a quick look at my system in the links below, this also includes the overall brew day flow. I think you may pick up some ideas for how you want your system to be setup based on my HERMS brew day. My system has been modified over 13 years of brewing experience for quality and ease, this said it is still just one way to do things.
Unless you are stuck on propane with no way at all to change, I would use electric for the HLT. This makes things easier in many ways if you have power.
Second, if you do a two tier system you can eliminate a pump, less money spent equals more toys somewhere else.
Those would be my two major inputs. Below is my step by step flow on my system. It is a two tier, one pump, gas fired boil, HERMS system.
How My Brew Day Flows: