problem #1 Check for firmware update from Sony. Check medium on another burner if possible, maybe you got a bad batch. Try using another program, maybe your Nero is bad (You can always try ms burning by right clicking and dropping it into DVD drive).
Question #2.... Super multi drive like LG will burn all formats of CD and DVD's. If it doesn't say so in your specs, chances are you can't.
My gaming machine:
P4 2.8 GHz
2 X 512 MHz PC3200 in dual DDR mode
Intel D865PERL MOBO
integrated 6.1 MAX audio
Logitech duo MX mouse and KB
ATI RADEON 9800 PRO