Here's what I did for 5:
1) Last lemming mines in the first dip. This should make the second to last turn around.
2) Make the second to last lemming mine to the right out of the left chamber.
3) Make him bash through the OWW.
The crowd should be freed late enough for the basher to have gotten all the way through.
Ah! I didn't notice that you could free AND turn around a lemming in one step like that. Clever, but undoubtedly unintentional.
Here's my method: Start off the same, except mine at the second dip (don't ask why). Continue the same, except mine lower, so that you land on the metal at the bottom. Build over that, and bash. Mine to free the other group. Actually, I don't even know if this is the way I solved it initially...
And 6:
1) #3 builds in the first dip to turn around. (using the third lemming makes step 2 easier)
2) Make #1 build to the right from the left side of the chamber. There should be a space because #3 was removed. #1 should build until he hits the steel.
3) Make #3 bash out of the left chamber.
4) Build across the fire pit.
5) Now it is okay to release the crowd, make a lemming build to the left from the right edge of the chamber.
6) Make #3 bash through the OWW.
Now they should all go to the exit.
My method (uses all tools) is very straightforward:
1) #1 builds in a dip to turn around.
2) #1 builds over the steel to the left, becomes a floater.
3) #1 builds again to turn around, and is now facing right.
4) Bash through the OWW.
5) Build (2x) over the bottom pit to create a safe passageway for the rest of the crowd.
6) Use your last basher to free the crowd (which is stuck in the right chamber).
Hmm, what is the preferred method of "encryption" on this forum now?