Hi i aint been breeding guppies for to long but you will dif get some babies its usually 31 days till they have there babies the guppies will breed anywhere but when they do give birth i would suggest move the female to a new tank or put her in a breeders net. Selective breeding i dnt knw to much about but i knw just dnt crossbreed or interbreed:
here is a useful post:
http://www.fishforums.com/forum/showthread.php?t=4036
- Jonno