Urgent help with new greenhouse and unhealthy plants! :-)

Hi folks,
I started to grow various herbs and cherry tomatoes indoors.
I built a small greenhouse in the backyard.
Then, when the plants looked tall/healthy enough, I moved them into the greenhouse.

Please look at this link to pictures of the greenhouse and closeups of the plants:
Greenhouse Photos by Scraniel | Photobucket

Some problems I've noticed lately:
- The cherry tomato plants' stems are bent as if they've become accustomed to reaching for light that's somehow not reaching them. Also, their first leaves have shriveled and some have detached. A couple other leaves show signs of wilting and one leaf had weird light brown spots. Also, the stems have some purple discoloration starting from the soil base... is this normal?
- The first leaf of the chive plants has (or is starting to) turned white and dying.
- The cilantro plants, like the tomatoes, also have stems which can't seem to support them and they fall around the container. Yet, the leaves are still green, but since I put them in the greenhouse, I noticed their leaves have started to appear unhealthy (withering and brownish tips).

Please help! Please look at the pictures for a better idea and I'm dying to know what I can do?

Perhaps open the ends of the greenhouse for air flow?

Note: I've been trying not to water the plants too much, because the soil in the small plastic cups containing the chives and cilantro is always damp. The tomato plants' soil is dry. How often should I be watering these?

Thanks in advance!