Hey,
If I have a sampled drum loop, I usually always eq out the bass so that I can add my own; I like techno kicks, nice and hard which acoustic kicks don't give me. Also, it allows me to place the kicks on a different track in Cubase and have full control over its volume.
Layering other sounds is such a good idea. First, it helps 'mask' the fact that you're using a drum loop and makes it sound more original than just the drum loop by itself. Second, it allows me to bring in and take out sounds during different parts of the song, making it more dynamic, just like if a real person were playing the loop.
Take care,
Nick