I am pulling a lot of data from a Word document into Sketch, and would like to know whether its possible to align parts of a text layer both left and right, without having to separate them on individual layers.
Unfortunately, no. Everything in the Alignment, Opacity, and Blending sections of the inspector apply to the entire text layer. The rest apply at a character level.
Yes, you can. Just select the target paragraph, then change the alignment or other properties.
But this is not a proper way to maintain your document, since it's very easy to mistakenly apply the text style to the whole text layer.