1. I'm not sure what you mean here. Is it that OP murdered Reeva and then invented the intruder story to avoid bad publicity and loss of earnings because of a complaint she might make?
Reeva was screaming her head off at 3AM in a quiet rural upscale estate... Neighbours were calling security...
OP realized that if Reeva kept screaming, security/police would eventually be knocking at his front door and they would want an explanation for the disturbance from both parties (OP and Reeva)... at which time Reeva would most certainly lodge a formal complaint (let us not forget she was a victim of domestic abuse from a previous boyfriend AND she was a guest speaker at a high school that very morning on that very subject)
Therefore OP had an escalating imperative to silence Reeva... but the more he got angry at her because she would not stop screaming, the more she got terrified of him and what he might do to her and the more she screamed... this escalation spiralled out of control until OP lost it and shot her.
When your pay check comes from your public image you are very much aware of the impact a domestic violence complaint from Reeva would have on your career : media frenzy and loss of sponsors.
2. A crime of passion is perfectly possible but what is the convincing evidence? The small number of messages suggesting a problem would fit right in with a crime passionnel but in themselves are unconvincing.
Much convincing evidence was led about OP's very short fuse and reckless/confrontational attitude towards others.
I don't know what kind of evidence you expect to obtain in such a case ?... a long documented and corroborated history of OP physically abusing Reeva ??... otherwise, we can't infer it... let us not forget proving motive is not necessary.
An argument about "who cares" between boyfriend and girlfriend escalated and boyfriend shot and killed girlfriend... the only way we could know anything about said argument is from the 2 people involved... but one is dead and the other stands accused of murder.
3/4. I don't know the statistics but in my experience fights tend to occur at closing time rather than when the pub opens. Not that I'd deliberately spill a man's pint to prove the point but it makes sense to me that loss of control followed by murder is much more likely if there is drink involved.
IIRC there was no evidence that OP was under the influence of anything. If the police had noticed anything in his behaviour in this regard then I'm sure they would have spoken up.
Why are you mentioning pubs ??... how is that relevant ?
Many millions of individuals intoxicate themselves to various degrees with alcool and/or drugs every day... BUT only a extremely small fraction of them act violently.
A few billion individuals do not intoxicate themselves... AND an extremely small fraction of them still act violently : road rage, spousal/child abuse, bullies, rape victims, etc. etc.
The whole drug/alcool argument or lack there of is specious.
Had OP drank a few beers, would that have made him more likely to have killed and more likely to be found guilty of murder... NO
Had Reeva drank a few beers, would that have made OP more likely to have killed her and more likely to be found guilty of her murder... NO
It seems to me that it is about the weight of evidence rather than a hard and fast rule. Of course he could have become angry and then murdered her without being under the influence but it is less likely. This makes it more difficult for the prosecution to say "this is how it happened and it could not have reasonably happened any other way"
BiB... that is not only an inadmissible inference but an incorrect one at that... some are mean drunks others are mellow drunks... alcohol does NOT equate to violent behaviour.