My guess is that after Don bought her the boobs he also bought her the "Introduction to Doxy" wardrobe to go with. Going to work for Tyler and finding out her sexual energy was profitable sealed the deal; hence a closet full of eye catching stripper casual that appeals to Don AND all the other men she attracts like flies to honey.
Grinder$ coffee mugs and more!
Also, regarding the poster I'm glimpsing on the wall: Not really surprising that Donna is a fan of that particular movie...
"Yes, EVERYBODY."
man, someone founded a telemedicine service called "Doxy"! Google Search: use it or else!
As to your other points, yes, this is the bleak world that Donna was born into. But I have high hopes.
(unfortunately no)
That first panel...
...
It looks very Georgia O'Keefe