Pics 2 and 4 look like nute burn, pic 5 looks like just a lower leaf turning yellow this is normal pic 3 i don't know, maybe iron deficiency.
Check here:
http://www.icmag.com/ic/showthread.php?t=11688
What are you trying to do? By the time you're using your soil, it should be composted enough that the worms don't have anything to feed on.
My compost pile is outside. I'm sure some worms make it inside via the soil, but I don't think they live long.
The only things I can think of that would...
One of mine's about 2 years old.
Correct.
Most use 18/6 (I do anyway) just as good as 24/0, smaller electric bill.
Yes, constant topping/taking clones.
I take clones up to the second third week of flowering depending on the strain. I;ll take some bottom branches off so the top get bigger. Doesn't stress them.
Transplant whenever you think the roots need more room.
Happy growong