You could always find a pair of boots that are the color or a good base that you could recolor into that shade of blue needed and the only thing you'd need is to make the white piece at the top of the boot removable. Maybe they can snap on with the buckles you see on backpacks or some form or velcro or snaps and just make sure it's at the back of the leg so it's least visible. Making it from fabric and stuffing it so you can just roll it up your leg, pull on you boots and roll it down onto place, but that doesn't sound like it's hold very well.
As for the wig, you could make the bun type piece from stryofoam or a wire frame to give it shape and cover it in wefts. Either way, make sure you make some sort of stand beneath the wigcap so it can stand up straight as it is in the picture.
Hope that helps and makes sense ^^;