[BusyBox] Copy files via Telnet, or use FTP

[Jeff (Tiscali)]

Hello All
Excuse my lack of experience of BusyBox and Linux in asking.
I have just installed Busybox on an old P200 machine, and everything 
works fine, but I have a couple of questions, I can open a Telnet 
session to my P200 machine, can I copy files remotely via Telnet or do I 
have to install an FTP server on my Busybox system? if so which one?
My second question is why cant I su to root via Telnet.
Thanks

Jeff Allan