It's totally normal. Usually just characretistics of a strain.
That can be a sign but it can mean a lot of other things as well. Certain deficiencies can cause reddening or purpling of the stems. A lot of strains have purplish stems also.
Whoa! That is waaaaay too cold! How long were they like that? That's probably your problem right there! Do you have pics of them?
I would try and keep the temps steady around the 75 mark. 68-78 is where mine seem to be happy. Looks like you have a combination of things going on, starting with the cold - definately stunted them, possibly even damaged the roots. If so that could be causing a nutrient lockout. They look a tad on the overwatered side, and starting to stretch - possibly not enough light, either. What are you using? You need a minimum of 3000 lumens per square foot for growing mj, 5000 lumens per square foot is recommended. Are they bagseed? If so, and if you have the temps under control now, to be honest I would scrap 'em and start over. You have the growth of a normal week to ten day old seedling. At three weeks, it should look more like this pic.
Yes and no, I think you're better off getting more CFL's on them than the tubes - they just don't have the same penetration. They will do the trick though - I just don't know if you'll be happy with the results. Do you have a Home Depot or Lowes near you? Can pick up a four pack of the 6500K CFL's for about $12. Personally, I veg with 4x27w CFL's per plant, they probably overlap a little though because i actually have them set up 12 to a rack. I've been satisfied with the results though, at least until I can afford to go with MH.
Thats a good distence, but lumens don't ADD like that. I've seen it explained troughout RIU many times. You need the proper spectrum's, 6500 for veg, and 2700 for flower, or both all the time. You're CFL's ideally should be 42w or higher. Some ppl get away with doubling up on 23-27w but keepin them close is the key.