yes i never completely gave them up when i stopped breeding them. Fyi if you don't want tons of babies only keep males, if you don't mind being over populated then you can get females, but the ratio should be 2 female to 1 male.
Guppies are some of the hardiest and easiest fish to keep, however many types/lines have been really inbred which makes them not as hardy as wild type or wild crosses.
tropical flakes are fine, buy I love any Hikari food, so the Guppy fancy would more than likely bring their colors out very well. looks like you have nice tuxedo, they look turquoise from your pics.
I currently only have a planted tank of wild type gups.
Lavender and white female Ct Bruiser, blue ct female Boy
red vt female, Dumbo ear Butterfly male Cloud
RIP ~ Cheeto, Pineapple, Shela, Double tail, Big blue