sorry to split hairs, but God did not create us foremost to serve Him. He created us foremost to glorify/love Him. If serving Him were the main reason, He could have made robots. and your Romans quote seemed out of left field to me. with love but this stuff's important.
As George H W Bush once said in a debate....that was about as clear as the boston harbor. LOL! Just kidding!
#1. Your first sentence answers what we were discussing. Sounds to me like a purpose. #2. God gave man from the beginning the knowledge of good and evil, therefore your robot is a non-issue. #3. My Romans quote was fitting but I guess you don't see "called according to his purpose" meaningful to this discussion. #4. Check out these verses and then tell me we are not called to serve Him: Exodus 7:16 John 12:26 Colossians 3:24 Hebrews 9:14 Even when we are in heaven we will serve him. Check out this verse: Revelations 7:15