plugins and uploads

Hi

I am a fairly new user, who is trying to figure out how WordPress works. i am amazed by it, it really rocks, but I have a few questions.

First of all let me clarify by saying that my wordpress blog is on the wordpress site. The address is https://jeebeez.wordpress.com
I haven’t yet figured out how to move it to my own domain

1. How do I manage plugins?
In older versions of WordPress there was a plugin menu in the backend.

2. Is it possible in any way to upload files (plugins, themes and such) to a blog on https://yourname.wordpress.com or do you have to have it on your own server?

I hope my questions are clear, otherwise please let me know ??

Thanks