You will not get narrow estimates on these drawings. Since these are "dreamer" drawings, you will get "dreamer" prices (meaning contractor is "dreaming" of that boat).
Two things which could derail this scheme from the get-go, so check zoning:
- lot coverage (impervious or built structure)
- 2nd driveway/curb cut
- a higher roof height for the lift or a street facing/or commercial style garage door might not pass an HOA
There are some real big ticket items that most people would try to design around to save some money (or not spend it wastefully).
- gas, electric, condenser move
- you show tearing out the existing back exterior wall. So you would have to add significant structure, the roof slope might need continued (and limit ceiling height), and all your homeruns terminate there.
- the office will have light/ventilation requirements in residential (needs an ext window)
- the server room cooling (I'm guessing because soundproof doors), could be substantial.
Just throwin it out there, can you build a detached on the other side of the driveway?