s-off: is that a feature that can be set back to s-on once all is done? Isn't there a security risk leaving the phone at s-off?
Not at all, all S-OFF does is enables write access to the phones recovery partition, enabling installation of custom ROMs.
As has been pointed out, it's needed to root too.

but my phone still s-on because i cant pass the step 16 that u mean "download the file"??,i dont know what to download,i so noob...

