1)if you drag to the left, anything the box touches is selected. Drag to the right and anything completely inside the box is selected. You can also click individual items, and you can select multiple items. Shift + click deselects individual items.
2) AfaiK, it's always been dots. At least it has been for the past 10 or more years. Don't think you can change it.
3) Never heard of them?? And I've been using AutoCAD daily for about 15 years.