Judging by the varying thicknesses it looks like gauging devices, most likely for sounding. Not sure why the tips are curved...but then again, I lack a penis so it's not like I'm an expert on the subject.
The one's designed like that are. Like anything there are different preferences. Going that far usually has the intent to hit the "p-spot". Same as with anal.
Oh. The one time I had a catheter put in I did not enjoy the journey down, or the soreness afterwards. Also, there's a big risk of infection for that sort of thing too. Sometimes I just dont understand people.