Yeah...you are definitely reading a different series.
ot: Itachi was a pacifist and really didn't do anything for them, other than help seal bijuu. That was only because he had to though, so he would not blow his cover.
He didn't murder anyone for Akatsuki. Kisame and Itachi didn't randomly go around killing people. Itachi upon his visit to Konoha avoided killing any shinobi and even made excuses to get out of there as quickly as possible. That should tell you about what type of shinobi he is.
The only member to go around randomly killing people was Hidan, because he sacrificed for "Lord Jashin" and Sasori because he added puppets to his collection. And Kakazu would steal money.
Each Akatsuki member only had one mission in Akatsuki. They were each assigned a bijuu to capture. Itachi was assigned to capture Naruto, but he purposely failed at that. The reason Naruto isn't dead as of now is because of Itachi. Itachi is basically the reason why the Akatsuki didn't take over the world sooner and require all of the bijuu.
Itachi didn't help the other members with capturing their jinchurikki. Kisame, Itachi's own partner, asked for help to capture Roshi (the carrier of the 4-tails) however Itachi refused. Kisame then went and captured Roshi himself.
Hiruzen stated that he was the one who asked Itachi to join Akatsuki as part of his mission as a double-spy. Obviously, since Hiruzen ordered him to join and said that he did a good job at it, that means Itachi did initially share info w/ Hiruzen, however it was never revealed what it was. He stopped the Akatsuki from getting Naruto, and due to Itachi being alive...Obito did not dare touch Konoha for years.
Irony.
Akatsuki were actively doing missions for a cheaper price than the other villages. Itachi is not exempt from these missions, especially if he's trying to maintain his cover.
Itachi doesn't kill needlessly, no. However, he does kill; he was even made captain of the Anbu... Konoha's team of elite assassins. Itachi does kill. Being a ninja, he has to.
That's what we know they did individually, but we're also told that they did missions which would require them to kill. They also killed Jinchuuriki, and would also kill anyone in their way.
In regards to your next paragraph, let me reiterate; Akatsuki was a group of ninjas which did work as ninjas for less than what other villages were charging. Onoki admitted that he used Akatsuki a lot in secret, and that they were cheap and got results.
Itachi was actually assigned to capture Gaara and tried to grab him during the Chuunin exams. However, when Itachi and Kisame got there, the exams ended early (because of Orochimaru's attack) and Gaara had already left. So, Itachi convinced Kisame to help him grab Naruto instead. If not for Jiraiya's arrival, Naruto would have been dragged back to Akatsuki by Kisame with nor arms or legs.
Also, Itachi broke Sasuke's arm and ribs, choked him, told him that he was weak and to kill Naruto to get stronger (MS), and then mindraped him into a drooling mess helplessly watching his family get murdered over and over again for what seemed like days.
Itachi did nothing to stop or hinder Akatsuki, and the war is going on right now with Obito/Madara having all the Bijuu in part thanks to Itachi's contributions.
Itachi did help Kisame capture Roushi. Notice Kisame said "you didn't fight him directly." Notice anything? If Itachi didn't help, then Kisame would had said "you didn't fight him." But, he didn't, he said "directly."
All the info Konoha had about Akatsuki came from Jiraiya, and even then it was 10 years after Itachi joined Akatsuki. Itachi did nothing to stop Akatsuki from getting Naruto, in fact Akatsuki had to save Naruto for last anyway as to not upset the balance.
If it was Itachi, it would had been really nice to tell everyone that the group was led by "Madara" (which was enough to get all the villages to work together) and that it's members included someone with the Rinnegan, and also who all of the other members were along with information about their abilities. Instead of everyone finding out the hard way, like Asuma and Jiraiya did.
And lastly, Itachi is NOT the reason Obito didn't attack Konoha; that was a sham deal. Itachi thought that the masked man was Madara whom wanted revenge against Konoha and made that deal under the pretense that Obito was Madara. HOWEVER, Obito did not give a shit about Konoha, he only cared about the Moon's Eye plan. Hell, even after Itachi's death, Obito still didn't give a shit about Konoha and kept working towards his endgame.
What would Itachi had done to stop Obito, anyway? Kill him? If Itachi were capable of doing that and saving Konoha and Sasuke from the very beginning, he would have.
You are in great denial about Itachi.