Why RJ killed Lorelei? Just because she gave the hanshake information?
I don't think so.

If not, why didn't he killed Rosalind after she gave a full description?

She is really blind or is she hypnotised?

I really hope for answers and not something like LOST ending...

The blind woman that used to be red johns lover, Harker Rosalind. She has popped up in a few episodes, and has the perfect cover. She's blind, therefore physically implausible to commit these crimes. But what if she wasn't blind? She would be able to commit these murders. She also has red hair. While this doesn't mean that this is the primary cause for her being red john, many red heads have nick names relating to their hair. Harker would be the perfect red john because viewers are shown how incapable she is, requiring meticulous motions and touch just to live out day to day life. Everyone discounts her as a suspect because she can't see. But I think this is a ruse, so that no one suspects her. When Patrick first began making a list of people that red john could be, after the hint from Lorelei, he didn't count women, because an assumption that red john was male was made (this was due to being referred to as 'him', the statistical likelihood of red john being female, and john being a male name). What better way for Harker Rosalind to cover up her being red john?

Rosalind Harker is the mastemind behind the Red John Organisation and she comes from the past of Jane's life.
Red John is Jane's opposite even though more than a single person, Red John is an Organisation. Jane himself is the cause of some of their crimes. Both good and evil, angel and demon, come from Jane's past, like Jane himself, first he was a fraud and conman, then a person who helps other people.
Rosalind Harker herself is connected somehow to Jane's past and Roy Tagliaferro and the others are simply the executors of her plans.

Harker Rosalind....she is able to I.D. because she is fond of him. PJ should gather the suspects and have her I.D. each of them that'll determine who if any of them may be RJ. Case closed.

Looking more at Rosalind as Red John, so many things point to her in 1.23.  Jane and Lisbon first meet Rosalind on her doorstep and Jane says he is looking for Roy Tagliaferro. He says "We believe he could be a serial murderer named Red John."  Then Rosalind says "No. Thats absurd" and gives a very suspicious smile.  At that point she knew she had Jane and Lisbon on the hook and could sell Tagliaferro to them any way she wanted.  She later runs into her house, presumably to escape the 2 CBI agents at her door, so she runs to her upstairs room as if that room is her safe haven.  It happens to be the room with the smiley face on the wall and she lead Jane right to it to show him. 

As is that wasn't enough, the very next words out of her mouth after Patrick sees the face, are "I'm blind, but I'm not blind."  Everything in that scene is set up so that Patrick would be completely misdirected when it is revealed that Rosalind is Red John. 

A sidetrack from the evidence for Rosalind over to the evidence that Jane has on Red John. 
-just under 6 feet tall
-short straight hair
-gentle voice
-not muscular, not soft

All of these characteristics are being used to pin down people on Jane's list of 7, but all of them are based on what Rosalind told Jane. 

*A quick note also on how the smiley face is drawn with closed eyes*

-and Kudos to the theory showing that Rosalind slipped Fur Elise into their conversation and smiled after saying it.

I'm not gonna give you my clues, the only thing that i'm gonna give you is time.

Time to think.

Rosalind Harker is Red John.

Hey

I've been watching 1x23 again, and noticed something weird:

@ ~17:54, they read the letter that Rosalind wrote to RJ Solutions: 

"Dear Roy, I found this address on a business card of yours that I discovered down the back of the sofa."

Isn't she supposed to be blind??

++