UpNorth, I think you might be thinking of the wrong sort of shorts. What Reeva was wearing was a set of sports vest/shorts things - the shorts were referred to as 'pants' by a couple of the witnesses. Think the sort of thing that runners tend to wear in the Olympics these days or for exercise, rather than going-out-in clothes.
So she wasn't naked, she may well have slept in the set she was wearing because it was light, but she may well have wanted to put a pair of shorts in rather than wandering around at night in what was little more than underwear.
As to why she never got out the house - that's complicated. If there was a row, it was very late, so maybe she wanted to wait until morning. Maybe she didn't want to leave him in a row. If it didn't get full on and violent until after OP had locked the bedroom door and set the alarms, that would have made things more tricky - you're asking her to get past an angry OP and a locked door and alarm to do so. It seems to me more likely that she'd run to where-ever was easy and 'safe' until he calmed down.
Nerf, you're right - I am not convinced by either side. I don't believe the intruder, and I'm not sure there is enough evidence for the row either. But then, how much evidence do 'rows' leave?
I think it was murder not because of the row, but because he shot four times with an extremely dangerous bullet. He intended to kill.
It is hard though. I want to be clear minded and stick to the things that we know for sure, but as some of what we know for sure completely relies on OP not lying, that is quite difficult.
If the testimony from Tasha's is to be believed (and I really believed the young boxer), OP lies to get himself out of bad trouble. His immediate reaction was 'say you were holding the gun'. That was his go-to response.
So discounting him for a second, we have a group of witnesses who heard a woman scream. Four of them heard a woman scream and then gunshots. Some heard bangs prior to the gunshots, but they heard a woman scream.
Then we have another set of witnesses who heard nothing at all until OP called for help from the balcony. They heard no screams and they heard no gunshots. They didn't hear much of anything. I assume they had excellent double glazing.
Then we've got character witnesses who say that OP was volatile, difficult, got angry and shot guns. There's no surprise there; I'm pretty sure you could find people who think I'm a terrible, chaotic, incompetent person, when in reality, I'm amazing. 
Conversely, there are a set of witnesses who think that OP is the most caring, wonderful, amazing person ever.
All of them saw the Oscar that they saw.
So yeah; it is just really, really hard to know.
What I would really, really like is for Reeva to have been calm, relaxed and happy until the second that the first shot went off. I don't want her to have had such an awful last few hours. That's probably skewing my thoughts. Equally, I really, really don't want OP to get away with murder if it is murder. So that's skewing them in the other direction.