ok, I've been into some similar situation so here are my tips:
1. learn to use the key editor (piano roll, whatever) in ableton. Take a good look at the manual, memorise and practice all the key commands (like the ones setting quantize-steps, ctrl-b for switching from edit mode and bact, etc...)
2. i guess its straightforward, but use impulse and simpler. if you use impulse, you can still control each sound from a separate midi-track, and that could come really handy later on when you want to develop your drum tracks further
3. i usually construct my drum tracks on the page with the clips (not arrange). you can make a clip with double-clicking on that excel-table-like thingy (yeah, I know I suck when it comes to the correct live "phraseology") and you can change the length to 1-bar 2-bar, etc. That is good to make some cool interworking patterns, coz once you start a clip, it will loop endlessly, but if their length is different you get nice interactions.
4. ok, the above works for redrum-like drum-machine stuff, but what about sliced loops you might ask. Now, here comes the fun part. You load the loop into an audio track under arrange. You can dissect it by hand, by setting the cursor with the mouse and pressing ctrl-E (if my memory serves me right). So you cut the loop up and then you can drag and drop those pieces into impulse (or simpler)! And from that point you can use impulse just like the famous dr rex.
5. make good use of those clip-envelopes. you can have clip-envelopes for effect parameters as well, so if you stack up an ampsim on an impulse, you can change the ampsim plug's parameters with teh clip envelopes. Get boogex from voxengo, its free and pretty good.
cheers,
Rags