past perfect necessary

hello teacher

Check that paragraph

A: Are you alright? You look tired.
B: Yes. I am. I didn't sleep very well. I 1) ...had Just gone.. to sleep last night when a lot of noise outside woke me up. I got up and went to the window. I 2)had been standing there for a few minutes when two police cars stopped outside my house. I went downstairs and a policeman told me that two prisoners 3) ....had escaped from prison and were hiding in the area.

I just wonder if 2) could be" was standing" there for a few minutes when two police cars stopped . Does it change a lot in the meaning?
I think in one case with past perfect the action of standing is finished ,it is a kind of flash back . In the second case there is no flash back, the action of standing was in progress was not finished
Last question would" stood" be ok if the author had written
I stood there a few minutes (action completed) when the police cars stopped . The order of the event is clear. First I stood then the police cars stopped.

Thanks for your answer