I used this wig in 24_H613:
And it looked like this on:
It was very nice/high quality.
There are options out there but it was surprisingly hard to find for such a simple hairstyle.
As for the coat, I found a few potential ones using various combinations of the search terms 'purple' 'leather' 'faux leather' 'bomber jacket' 'PU' (short for polyurethane) etc. While none are exact, most are close enough.
For the gun, you can buy Nerf gun (like the Stampede mentioned above) and tweak/paint it, then attach a strap to carry it with.
Little details can also make a big difference - silver hoop earrings, a "Tardis key" , makeup, and of course a big Rose smile!
Hope this helped a bit. Good luck and have fun!