B, C, D & E are correct. You are allowed to continue play with the provisional ball whilst walking to the original position, so long as NO shots are played from in front of where the original ball is deemed to be. With A, you are quite correct in that due to nominating a PROVISIONAL ball from the tee, until such time that you state that the Provisional is now in play, your first ball is still active until the end of the 5 minute search or it is found OOB. If after seeing that the Provisional ball was so good you wished to continue with that one rather than look for the first, you should have, after leaving the tee area, made it totally clear to all parties that you were deeming the original ball LOST. Obviously if you do not do this and someone finds it within the allotted time you are bound to play it no matter how gruesome the lie may be.