shit this sucks so 4 of my 8 plants are male so far, and the others could be male for all i kno because they have yet to show anything having bad luck i guess.
Don't get your hopes up, you're males showed earlier because well that's what males do. Females take long to adjust and start flowering! Good luck mate!
As for re-using soil, put some in a 50/50 mix of old and new mix, and place some in new mix. See which plants do best. This will determine if your soil quality is re-usable or not, although i doubt it.
Not to sure but, i grow hydros =)