how to adjust the metronome?

[badgrplayer]

Hello,

I'm using Mulab 7 free version to create a midi drum pattern to go with an audio sample.

The first thing I try to do is to find the right tempo.
So I import my audio file, and I play it along with the metronome until I find the correct BPM.

Problem is, audio file's tempo change with the metronome (on the grid, it stretch or shrink). That's what I want; I want to find the correct BPM, for instance 88 BPM, and then create all my tracks on the same BPM in 4/4.

So I've start to mess around a little and now I have a correct rythm for the bass drum but the grid repesents 5 bars when I want only 4 bars. If I can't change the tempo, can I change the grid and how?

By the way, why is there a "set part start" marker but no "set part end"?

Thank you.