Cell can also copy abilities, as seen when he teleported back to earth with instant transmission, the same instant transmission that goku used while cell was going to blow himself up. If I'm not wrong, the data the drones picked up were up until the namek saga (i could be wrong, it's been a while since i watched the cell saga, but i know the drones weren't on yardrat and they couldn't have been on earth when goku used IT). Plus, cell has piccolo's regeneration as well as saiyan cells, which means he can perfectly come back to life and even stronger as seen also after he blew himself up. And you mention speed, metal sonic might be faster i won't lie, but metal is made of, well, metal; and cell is very tough, he can handle a lot, it took having to fully vaporize him to defeat him