So all the below in 1 TU
Enter the location and read card A
Decide on the card and read
3 players are locked in but the 4th picks up an item.
1 TU spent for the 3 to fight but the 4th hasn't rolled
Can the 4th move which is an action and look at a new card or can you not read that card till the next TU spend?
Your accounting and sequencing is slightly off, for 0 TU...
Lay out the panorama.
Read card A.
Decide to enter (or leave) the location.
Place pawns on spaces.
Read the appropriate cards (collect Items).
Then (if you must, because of locks, or choose to do so) spend 1 TU to move, attempt a test or do nothing.