For the round holes, you can switch between drill bits and hole saws. To trim and adjust the holes, use a rotary cutting blade with a pneumatic die grinder. You can check an article comparing Milwaukee and Dew
Dry install tiles or use a “story pole” (a stick with markings that reference stacked tile seams to help plan tile install) to adjust your base starting height to facilitate tile seams falling on desired targets (the window ledge, for example). You can also build a wall model away from...