yeah i suggest u ditch kies. use Odin to update firmware via this guide
[ROM + Guide]Official i9100 Firmwares KF1/2/3/4/, KG1/2/3/5/6/7 Download - xda-developers
i recommend KG5 (OXA Poland) which is the newest official firmware, its android 2.3.4 and much better than wat kies just updated ur phone with
for transfering data, just plug in ur phone via usb and u should see it appear in ur Computer as a device. if u plug in ur phone and u see "MTP connected" in ur phone's notification bar.. u should see it as a device on ur computer
if u see a USB connected, u have to select it and choose to mount ur memory to the computer, and then u will see it as a removable drive. then its just drag n drop afterwards
hope it works for u! oh and welcome to the forum