Thanks so much for your input, Adam.
As for a new machine - I’ve really busted the budget on the Shapeoko 3, SuckIt dust boot, Elaire 1/8" collet for the Makita, and a bunch of end mills. In any case, I’m one of those geeks who won’t buy a new computer unless I absolutely must, and I’m just not there yet!
At your suggestion, I took a look at Makercam and I’m going to play around with it. However, I live in a rural area, and my Internet occasionally goes out, so I’d prefer not to rely on web-based tools. Easel may be a better fit for me in that regard - I think I’ll play with it first. Since I can’t run Carbide Motion on that laptop either (perhaps, like Carbide Create, also due to the Mobile Intel® 4 Series Express Chipset video processor) I’ll definitely check out grbl-panel as well.