"Is there any chance that a Ukrainian military transport would be heading East into Russia, as MH17 was? Is the Ukrainian government on good enough terms with Moscow for that to be possible?"
no, but there is a chance it would be heading to a group of encircled ukrainian soldiers where they would drop them supplies, actually that did happen several times before the crash
I know that supplies are not dropped from FL330 but it's questionable if rebels knew it or even had means to precisely measure the altitude because they didn't possess an auxiliary target acquisition radar vehicle, just an embedded radar on their launch-vehicle which is rudimentary at best.
they have seen the blip and were trigger-happy to fire before checking on something they were convinced was an ukrainian Antonov transport plane because it came the same route
"I don't suppose anyone here could have a look and see if Aeroflot started avoiding the area just after the Buk missile carriers arrived?"
IIRC they have overflown the Ukraine many times that day however not exactly the same area and not in direction coming up from Kiev so practically no chance of misidentifying with ukrainian military aircrafts... you could expect their pilots to know the situation better than others (it was all over their news that rebels have got the BUK system) and go around the area on their own.