?'s about 18/6 - 12/12 cycles and clones

I have a 600W HPS and a small 150W incandescent. What I want to do is grow/maintain clones with 150W while other plants are flowering. Is this light good enough ("daylight grow bulb") for the clones during the period that I am flowering the other plants?
Also, how does sexing/flowering work exactly? I understand that 18/6 is for veg stage and that 12/12 is for sexing and flowering; however, when you sex the plant at 3 weeks do you switch back to the veg stage after sexing OR do you just continue with the flowering? Essentially what I don't understand is if you start with 18/6 and at 3 weeks begin 12/12 to sex do you then revert to 18/6 for the veg stage OR if once you sex the plants at 3 weeks you just continue with 12/12?
1 more thing - when do I take a new batch of clones in order that they will be ready to be taken off the 150W and put on the 600W just when the others are ready to dry?
any advice would be much appreciated

It depends on what you wish to do. If you JUST want to sex them and let them get bigger before you flower them. then you'd go back to 18/6. If you want to continue to flower them and get ready to harvest. you stay on 12/12 all the way through. BTW an incandescent might work for clones but I'd suggest a CFL. You can get them at any grocery store. It's not a good idea to take clones during flowering and if you took them before that. By the time your original plant is done they will be pretty big and way too old for that 150 watt incandescent.