I am 11 days into my Auto AK47 grow....FFOF soil. Have not added any nutes...but my boy is growing in DWC, he is a month ahead of me, and I swear his plant is almost 3 feet tall, no stretch, with a HUGE COLA. Had I seen how big his auto was getting in DWC, I would have definately gone that route...
As for improving yield, get the highest watt HPS you can afford, get it as close to the plant as possible without burning it. More Lumens=bigger, stronger plants.
Use good soil, ferts, controll your airflow and temps. You know, basic gardening shit bro.
As for LST, FIM, Topping and all that stuff, I have yet to try it, or seen a grow journal with pics on any method with a Auto plant. I would love to try it, just do not have a "spare" plant that I want to experiment on this time around....maybe next time.
GL!