They sell firewood for open fires in the Glen Rouge campground at 7450 Kingston Rd, Scarborough and I have friends with a fireplace on Whites road which is even closer towards downtown, so it must not be a significant law or insurance issue in Scarborough ymmv.
To the best of my knowledge; firewood is HST taxable unless you cut it yourself on your own property, or collect free cutoff scraps from some woodworking type business, or possibly cut up and burn old wooden pallets. Everything related to cutting, transporting and the initial fireplace installation is also taxed so you don't need to feel too badly for the tax collector.