For me your #2 is the deal breaker. If I have to box a bunch of stuff back up and drop it off somewhere it's more hassle than shopping at a brick & mortar shoe store. There would have to be a huge price advantage to make it worthwhile.
There are so many delivery services... there should really be an inverse. "We'll pick things up for you." I bet Shyp could branch out into this, though it's clearly not their target scenario http://www.shyp.com/
Its already a thing, but its expensive so tends not to be offered, although Amazon will arrange pick up for a small fee.
Most of the shippers happily pick up boxes from you. I have ups pick things up at my house all the time. Just put it in the box and stick the pre printed return label on the side.