This evening I was back on The Project. After getting bored of trying to implement my own line-drawing algorithm from memory I just grabbed this one and plugged it straight in. Remember kids, always check Gamedev.net first! Ahem. From there it was a simple extension to add in the map-checking code, turning a line-drawing algorithm into a visibility checking algorithm. Visibility is going to be a key aspect of this game and you will want to position your squad members out of sight but with as much of a view as possible. Similarly I will make the AI take visibility and cover into account when deciding where a unit should be positioned and which way they'll face.
The other point worthy of note is that I added this functionality while running my Mandrake 10 installation. Getting it compiling with g++ took no more than 30m, so now I can code this from the more stable environment of Linux, as well as get the benefit of another compiler's set of warnings, and produce a Linux executable for anyone who's interested.
The next unit of functionality is probably to add a rudimentary Character type (just a pair of coordinates and a path), change the current pathing to store the A* results in the Character's path variable, and use an SDL_Timer to move the Character along that path once every 300ms or so, a tile at a time. From there it becomes reasonably trivial to have several Characters doing that simultanously, and the gameplay will start to take shape.