Dip N grow is very cheap and it's my understanding it has a cult following of sorts, $8.95 for a bottle of highly concentrated stuff, I was 9 for 9 with my clones the first time I ever tried cloning.

I have never tweaked with lighting but I do not believe you'd have a problem increasing it, just don't go below 16 hours/day.

There is much debate about what the dark period does for vegging plants and I have no idea, my halide only goes off for moves/res changes.

6 to 8 weeks should be enough time to grow that 12" needed to start flowering, maybe not even that long.