Seni is "you" as object, sana is "to you", or something like that.
Yes. And here it is something like "I (ben) will give (vereceğim) news (haber) to you (sana)".
A typo . You meant : Sana :)
Indeed. Thanks! Fixed now.
How do you know whether to use seni or sana?
Seni (you) : Seni seviyorum . ( I like you )
Sana (to you) : Ben sana haber verdim . (Literally: I gave news to you)
Ben seni bildericegim