I like to keep my plan chronological, but sometimes I have to add a task after I've finished planning my day. Can I move it so it's not at the bottom of the list?

Yes, you can reorder the items in your plan whenever you like.

Simply hover over the item you’d like to move and you’ll see a set of two vertical ellipses to the left of the task‘s timer. Click and hold those ellipses to grab the item you’d like to move, then pull it down or up to get it where you want it in your plan. The dotted line shows you where your item will land. When you’ve found the right spot, release to drop the item in place.