What is the correct method to round a face? Is it possible to 'align' sketch edges?

I’ve been trying to figure out how to round this face in this drawing. I want to round it ‘outward’. Basically so it’s rounded out and meets up well with the front and back of the shape.

I feel like I must be missing something obvious. Is there a way, other than trying to draw a sketch and butting it up to this?

Part 2. When sketching, it is possible to move a line, but have it snap to another line? Like the align tool that works between bodies?

I appreciate the learning. Thanks.