it is perfectly normal for cories to sit at the bottom, as they are bottom dwelling fish. mine will just sit in one spot for long periods of time. nothign to worry about usually.
cories do best in groups of three or more, so keep that in mind. since albinos are really active little cories, a group of all albinos is a good idea, its fun to see them all playing together and shooting around the tank. cories will often school with other cories regardless of type, but some won't. i have four pandas who of course hang out together, but not with my other larger cory varieties. my two emeralds are inseparable, but my single spotted won't school with the two emeralds, though it seems like they try to get him to hang with them. he seems to just be a loner. he used to school with my network/reticulated cory, but after he died, the spotted stays to himself. long story short, you could try doing a mix and see, who knows, they may just school and be happy together.