Damn bro, you got nice plants for not having fed them yet. If you plan on vegging them for longer, you should find a nute with an N-P-K of 20-10-10 or likewise. If your gonna flower em now, you should get a 10-20-20 or similar (you'll need this one eventually anyway). Normally, start feeding them a half or 1/4 strength dose of nutes every other or third time you water. Eventually, (2 weeks or so) move up to 1/2 or full strength doses (if you went from 1/4, move to 1/2, eventually full strength). I recommend an organic fertilizer, as they dont burn the soil. Neptune's Harvest is a good example.
Remember, once marijuana starts flowering, they will about double in size or more, so think about how much space you have to grow, and that will determine when to flower these puppies.
As far as cloning goes, buy some take-root or rooting gel . Make a small slice near the branch armpit at an angle (not a straight cut). Spread rooting gel on the cut end and plant. Move them into a high humidity dome or keep them under plastic for a few days, water only by spraying them with pure water (no nutes), as they dont have roots yet! Its normal for them to look sick or struggling until they get their roots back.
Hope this helps, any other questions, ask away man, we are here to help!
MVNugs
