Hey Jerry, I’ll start with this: the current accuracy is about 0.1% per unit distance traveled. So for 300 inches of tool travel, that would equate to about 0.3 inches of error. Like you said, the design could be split up into multiple sections to refine the accuracy, but it would be up to you to make sure those all align. In terms of simple drill patterns, Compass is perfectly adequate. It’s a great use case, you just have to make sure the accuracy is adequate for your project.
There’s currently no way to do this automatically, but we have been scheming a couple methods. The sensors should be able to theoretically be used for edge finding. My current method, though, is to either align the edge of the baseplate with the workpiece (and take into account the offset in CAM) or use a 3D printed homing bracket for more precise zeroing. A touch sensor is an interesting idea, but I’m personally trying to explore solutions with existing hardware first. The origin is set as soon as you start your design, so you just take that into account when setting up your CAM.
This would likely be done with a physical corner bracket, but honestly for large dados and rabbets it might not be fine enough to provide adequate alignment. You can’t really “set the grid” without mapping the workpiece in some way. That might be possible at some point by inputting the size of your workpiece, but there’s no real way to do that super accurately right now.
You can set whatever feed you want in CAM and the Compass will hold that. You can also adjust the “gain” of that feedrate to go slower or faster while cutting if it needs to be changed. I’m not sure I can give an exact answer as to whether Compass would be able to cut a 3/4" x 1/4" dado in one pass. Are you using some sort of 3/4" dado bit?