Where is your best view? Do you have any obstructions on your lot? From your house plans, I can see only one place the architect has planned for a deck to be connected to the house. If you look on the left elevation, there is a "ledger" board drawn just below the French Door. It runs the full length on that portion of the exterior and if you look even further to the left, it continues on the next butt out. Switching to the rear elevation. The ledger board is seen on the right side where there is 3 levels of windows as well as on the short abutment just to it's left. I did my best to draw it in blur, forgive my shaky hands. Of you can add a ledger board to hang the deck off of anywhere on your house as well as converting a window to a door or just plain adding a door to use the deck. You can also have multi-levels, one for cooking, one for dining, one for the hot tub after the party leaves (or continues). I hope this helps, but I would talk with your architecht or a master deck builder for their suggestions. Come with your ideas as to what you want to accomplish.

Ash being a light wood but can be hard to stain in a darker stain since it's such a dense wood - I would consider staining with Minwax English Chestnut # 233 add coats until it gets dark enough to match adjacent wood stain , also consider a very flat sealer ( such as tung oil or satin poly no shine is important against the flat finish of brick

First pic is the deck after we have started painting the exterior of the house. The 2nd is our exterior paint colors. 3rd is the deck when we bought it. Do we paint it all one color?

it depends on what side of the house. A dark deck on the south or west side will get direct sunlight and HEAT UP, stay away from dark colors. if you are north facing, dark may be suitable. Staining over trex? I doubt it will be a good finish. as the manufacturer for thoughts.