why does it seem like people who work at hydro shops always have no idea what they are talking about? does he not know you are talking about cannabis? and maybe he thinks your talking about roses or something?

in flowering indicas will stretch to roughly be 2x the size, sativas are known to quadruple in size (and boy did mine ever.)

Yes. switch to the 1/2 bloom, 1/2 grow asap. Also, judging by that picture I am 99% sure that is a male.

If your only going out of town for 3 days, I highly doubt that at the stage the suspected male is at, that a mature pollen sac will open while your gone.

Also, its not recommended to top your plant if your about to switch in flowering (and never top during flowering). Your plants will need to recover from the stress of the top before you switch to 12/12, and that will only create more shoots, and you look like you have enough bush as it is. (they do look beautiful)

*edit*
also is that 2 feet of space whats left above the light (as in you can only raise the light up 2 more feet?)