This time Robocop has a different face. This is of course the result of Peter Weller quitting the role after Robocop 2, but the different face could also be justified in-universe with the battle damage Robocop suffered at the end of Robocop 2 by Cain aka Robocop 2. In that movie Cain brings an electric cutting torch to the Robocop's face, cutting a long streak on his face plate. It is highly likely that the molten metal damaged Murphy's face underneath and OCP technicians replaced it with a new face. Of course in Robocop 3 Dr. Lazarus mentions that Robocop still has Murphy's facial and nervous tissue, but she said that in Robocop's presence. It is possible that Robocop's facial tissue was replaced and everyone keeps this fact from Robocop to prevent him from freaking out of a further loss of his former humanity.
Also keep in mind that Robocop series of cyborgs goes from 0% freak out ratio to 75% ratio over the course of previous movie. OCP's perception of Robocop may very well have shifted from a perfectly reliable tool to a ticking bullet-spraying time bomb. In this movie the OCP official tells Dr. Lazarus to get rid of Robocop's emotions by installing a restraining chip, which already existed. That means OCP has dedicated time, research and funds into the freak out problem and were just waiting for an excuse to implement it. It also gives the propaganda feed of Robocop butchering nuns a lot more credibility. The OCP officials may have thought that they might be able to convince the audience of the last Robocop going berserk.
The battle damage would also explain why the directives are back: OCP slipped them in during the repairs. And given how ineffective the additional ones were, they just went to the original four, updating the fourth to better suit their goals and not bothering to hide it anymore as he already knew of it.
RoboCop mentions not having many friends, but seems to spend most of his time in the police headquarters basement or in his squad car. A bunch of policemen, his partner included, are hanging out in a doughnut shop near the beginning of the film and a few of them even ask his partner why he's not there, to which she responds something along the lines of it "not being his thing". The other officers almost universally still see him as the man he was before his death, rally to his aid in the previous film, and wonder where he is when his partner is sitting alone. It seems his perceived lack of friends is partially a result of him isolating himself.
When RoboCop walks in the police station to annihilate the Rehabs base there Reed just points him where they are, and no officer tries to stop him. The cops don't like the Rehabs, know he's been framed, and even if they thought he was out of control they know they can't stop him without enormous collateral damage and possibly loss of lives from any civilian in the station, so it was their duty, and pleasure, to send their friend to deal with the Rehabs with as little damage as possible.
Johnson telling the cops that they are jeopardizing their retirement benefits comes across as an empty threat to begin with, but in the previous film has a throwaway line on a news reports mentions that OCP already cancelled the cops' pensions, making this even less of a threat.
Otomo:
The first android didn't have a self-destruct device like the last two because that model was designed for stealth. Plus, if it did have a bomb and it went off unexpectedly, that would attract the government's attention and blow OCP's cover.
The behavior they show in their interactions was Robocop were likely set by McDagget, who even the CEO realized was insane, explaining why they never went right for the kill.
