The electric screwdriver can sometimes fit where a bulky drill cannot, e.g., electrical boxes. Apart from that, the drill is a fine screwdriver (assuming it has a clutch, of course, but I have never seen a battery-powered drill that does not).
Don't get rid of your corded drill. Battery-powered drills, especially the cheap ones, are not powerful enough for serious drilling such as a 5/8-inch hole through a 4x4 or any hole through metal.
That is a countersink. I would not call it a drill bit, as it's intended to open and shape a hole. Typically a through-hole of the smallest diameter is drilled, then the countersink is performed as a secondary operation. It is typically not advisable to try and "drill" a hole with a countersink.
Best Answer
Depends on the size/strength of the clog.
However, as an owner of a Hitachi 12v cordless, I find it quite strong as long as the charge is good, so probably.