They have to be small, otherwise you probably will hurt yourself. Still you'll be able only to trim the bush, not get rid of it entirely.
Ya, just trim it up. Think pruning the bush rather than cutting it to the ground. But really, you can get pretty close. You don't want to cut yourself though. That's a sensitive area.
Do you have a razor for your face? Most guys are shaving their face by 15 to 16. Maybe for your next holiday in which you receive a present, like your birthday or whatever, you can ask for a razor. Then you'd just have to earn money to buy blades. I wouldn't use that razor for downstairs though. It might dull the blade and you need a good blade for a close shave of the face.
I wouldn't try using them as a blade for full hair removal, especially in such a delicate area.
You can use the scissors to trim the hair, but be VERY careful. Cutting yourself with scissors will hurt.