Tempo of a sample?

First and foremost, how y'all doin'? I hope I can ask this question correctly. I have an MPC 1000 and I primarily sample from my keyboard. I use the keyboard to record basslines, strings, etc. I play it smart by recording theses snippets on my keyboard at the same tempo as the recorded drum tracks on my MPC. But the question is, is that really necessary? Like what if the MPC sampled me live, playing a 5 second piece with no real "tempo" in sight? Or when Kanye or anybody else uses a sped up RnB sample? How much does the tempo of the sample effect the tempo of the track itself? My concern is, when I go to the studio and my music is "piped" through their machinery, I don't want to be caught off guard, by everything sounding out of place. I hope I was clear with my question. Thanks for your time.