1. QUBE reportedly having loco issues with some G class, hence they still have to run the APEX (1 G) plus the Maryvale (another 2) using the 4 G class and one VL as their BG fleet. The VL is off to get some grain, so with 3 G already in use, that leaves only one for maintenance plus to run second unit on the grain, so that leaves nothing for the Toc/Deni (long-term contracts). Hence they have to hire one decent power loco for the grain, and whatever else they can source for the Toc/Deni. If they are going to retain contracts, they have to deliver, even if one train on one day is unprofitable. Standard business practise, wear the occasional losses to keep the larger business.
2. They used to run lash-ups such as S/T/T/T/B, but not necessarily all locos would be powering always. With that Toc (isn't it a Deni on Monday?) they would probably have at least 3 locos shut down or idling off-line to Murchison East on the Up; they have to stop there a while for the cross with the 16:31 Shepparton, and that's time to get the others started/on-line. Still not greatly efficient, but less expensive than it might otherwise be.
3. The Murray Basin job will free up heaps of BG locos for SG. Apart from QUBE's own locos, there are numerous locos available for hire on SG, and most of these are high horsepower and efficient machines. This may be the last year we see these consists in freight trains; it's a bonus for the preservation groups, who I understand have factored it to be only basically one season, and aren't making longer-term plans than that. Enjoy the sights and sounds while you can, it may be their last freight trips ever.
4. The GML, if converted to BG, would likely be as a replacement for another of the existing fleet (4 G and the VL), and would likely use bogies from whatever loco went back to SG. They did that with the VL (356?), which after engine failure was exchanged for 362 (?) using the same bogies. I understand the dead engine hasn't been repaired, and may not be. Nevertheless, QUBE are still running with only 5 locos of 3000hp, after that they have to lease. Back to para 1; they need 2 for the Maryvale, one for the APEX, 2 for the Deni/Toc. Still none left for servicing nor for extra trains. But then, if you were looking at a network about to go mainly sg, would you spend money getting more bogies for one or two seasons? Maybe you would hire the heritage fleet as well.