Right, i think it depends on what model you got, not sure,
but i have the 60gb one,
anyway heres how i did it.
my laptop has a wireless thing in it, if you have a PC with wireless thing that would work to.
try and find media servers on the PS3 under, video, Music or pictures, and find your laptop or PC, Put what ever you want into a shared folder, and then find that folder from your PC, now transfer it, or stream it.
If you dont have wireless, or cant do any of that,
then yes a USB stick works.
putting pics as wallpapers, get the pic onto you PS3 go to the pic, view it, scroll along the options while viewing till you come to set as wallpaper,
if you have the internet on your PS3, use the browser to get pics, copy them to your PS3 and do the same, you cant transfer music from the browser though. i dont think so anyway.
as for phones, connection, mines all pic up my phones bluetooth, by going to network, and going to accessories,
this is all wireless feature wi-fi,
if your PS3 model does not supprt that then the only way is USB stick
cant you rip cd to the hard drive. but your pic on a sd card or a digital camra useing the usb. but there just useing the cd player i know it so 90's of me. ge i wonder what you would say about 8-track tapes.