The only difference between female seeds and regular seeds is the chromosomes responsible for determining the sex of the plant. Potency should not be affected by that. They might be more prone to growing male flowers than regular seeds, but regular seeds do it too. I have not been very interested in many feminized strains in the past, but Caramelo is one that I had to pick up based on Barrelhse's pictures of it. Check it out Variety of Singles from Pick & Mix at Attitude- Pics
I don't know how I feel about multiple generations of feminized seeds because it seems like your selecting for hermaphrodism and they would become increasingly more common, but that's jhust a theory. There are many great strains that are the product of multiple feminization like OG Kush, Bubba Kush and Sour Diesel. Do a google search for collodial silver. It's really simple, the hardest/most expensive part will be acquiring a silver coin.