Machine quilting is certainly an option for a lap-sized quilt, even for a larger quilt. It is a very pretty quilt.
If you decide to machine quilt, I would first stabilize the quilt by quilting in the ditches where the blocks are sewn together. Then you can remove the pins and you will be able to do any other quilting that you want to do, such as the hearts.
3 inches or so extra batting all the way around is plenty. Plan for the same amount of extra backing.
Hand quilting is wonderful - I admire those who do it, but I don't have the patience.
Show us the quilt again when you're finished. I love the fun, bright colors.