Something I noticed aswell. You say you need to press the 1 turn building cheat on before you press the city? Do this:
1) Click city. 2) Hover mouse over building to be built. 3) Press Num 3. 4) Click on building you want to build. 5) The building should be added with 1 turn on it.
After you pressed Num 3 you will be able to select a few buildings and turn them into 1 turn. I've even pressed Num 3 sometimes and even after 10 mins the 1 turn was still on, provided I hadn't clicked on more than 2-3 buildings during that time.
Heres some, off the top of my head, cheat options you could think about:
1) 1 turn technology. 2) Force alliance. 3) Force Trade. 4) Force allies to aid in declaration of war. 5) Rotate wind position by 45 degrees. 6) Max out ship cannons. 7) Max out ship crew. 8) Increase selected unitís size. 9) Decrease selected unitís size. 10) Infinite ammo (Ship/Infantry). 11) Disable/Enable morale. 12) Disable/Enable fatigue. 13) Max range (Ship/Infantry). 14) Invincible/Tough General. 15) 100% Sabotage Rate on selected agent or event. 16) 100% Assassination rate on selected agent or event. 17) 100% Steal Technology rate on selected agent or event. 18) 100% Infiltrate rate on selected agent or event. 19) Max population happiness in selected city. 20) 100% King/Queen/President popularity. 21) Allow unit repair without need of city/port. 22) Selected city instantly becomes yours. 23) Allow defences to be built after battle has started.