The yellowing could be from anything. You need to step back from the plant a little bit, the pictures are too blurry. 2 x 150w CFLs would probably work great for you. The yellowing could easily be heat burn from the halogen lamps you had over the plants earlier. If the yellowing just started directly after you removed the lights then it must be some other problem. It also could have been from the spiders you had previously. I'm guessing it could have been a combination of heat burn and insects. Anyway, now you need to get some lights on those plants ASAP. At least just leave them in a room with the light on 24/7 until you get some lights dedicated to growing underneath them.
P.S. - You can start using nutes after the 3rd node has grown. Start with a 1/4 concentration and work your way up to full every new node.