Most prickly pears are very adaptable and tolerant of a lot of abuse/neglect. I do not know where you are located, but as long as these get plenty of light and in hot dry weather some extra water they will probably grow just fine. There biggest issue is sitting in cold wet soil for too long, but many prickly pears will take that for quite as well.
The purple color of the pads is an indication that the plant is a little stressed. Usually some form of low water high sun/heat or alternatively cold (like my Santa Rita goes purple in winter and while it does not really get cold here, it is a lot colder than normal). If it is water/sun stress some extra water may turn the pads looking more their original grey/green color.
Flowers on prickly pears can be very difficult, many species can have quite variable flowers so while flowers can help with the ID, it is not something that by itself provides certainty (well with some exceptions of course).