Guppy culls/breeder females

[lightningturtle]

I'm trying to create my own strain of guppies, but I'm still working out the technique. I've been doing culls of juveniles, but a few that I've kept have known wholly unexpected patterns. Any tips on when/how I might get a good idea of what the adult colors/patterns will be?

In addition, does anyone have an idea where to find decent swordtail females? I'm finding plenty of grasses, but that's about it.