Have astronauts in space suits ever taken selfies?
Were selfie sticks used?
If not, how was this feat accomplished?
The cameras used are large-ish but imagine even holding a shoe box in front of you with thick gloves on: you're still able to point it at yourself in a distance suitable to make a photograph of yourself, provided the lens' focal length/field of view allows to capture enough of your face.
At least some of the cameras just look like a normal DSLR in a special casing and can be seen in the helmet reflections like this one:
There is a nice gallery of space selfies at Wikimedia.