Never transplant from soil to any hydro late in the game... if you start in soil then leave it there... by transplanting to a different growing type you will cause serious stress and honestly will probably end up with mostly hermies.
Final Flushing is a very heated subject, many will say its a must where many others will say its a waste. I have truly never flushed any plant soil, dlood & drain or aeroponics for more than 3 days. What I have done in many cases is the last few weeks I begin cutting down my feeding amounts as much as 75%. I have always felt flushing is robbing a plant of nutrients, the reason plant begins to die off at the end is mostly due to lack of nutrients, not because it is suppose to. I prefer to get all I can out of every plant.
Soil plants my feeding schedule is - nutes-nutes-water-nutes-nutes-water-water
My final 8feedings schedule is - nutes-nutes-water-nutes-nutes-water-water-water