In my experience (disposing of a euc, not blue gum, that I had removed from my front yard), the euc wood might break your splitter if you let it dry first. Mine had a spiral-wrap layer under the bark that tied the whole thing together, and to split it I first had to cut through the spiral layer with a saw. Yes, once it dries out it then burns clean and hot - perhaps too hot for some fireplaces unless the fire is kept low with relatively small pieces.

As for the gasoline effect, I lived pretty close to a case where a grass fire got in under a few blue gums in a vacant lot and exploded. The trees went up like torches and it was all the fire dept could do to keep the houses up to a couple hundred feet away from going up too - they got pretty well scorched. And the fire didn't kill them; they resprouted and the last time I looked at Google Maps there's a good-sized forest of them there now.

They aren't even particularly good windbreaks (an alleged purpose of planting them) unless in a large grove. Individual trees are poorly rooted and blow over easily; it's only inside the grove that they hold each other up.

The people who promoted plantings of them in the late 1800s-early 1900s were either scam artists or abysmally ignorant. On the plus side, they *do* grow like weeds and have naturalized well, so if you want instant big messy tree near the coast they're a good choice. There are better choices...