I've always thought that some betta vases look very pretty.
First off, I'd suggest that instead of seeding with water from your other tank that you seed with gravel from the established tank. The nitrifying bacteria grow on surfaces, and very (if any) will be found floating in the water. Then I think that you should be set with the rest of the said set-up. Bettas don't produce much waste.
I know that you mentioned that you didn't want to add a light, but if you'd like plants, I'd suggest just getting a cheap desk lamp, and a screw-in PC bulb with an appropriate spectrum for plant growth. Then you could probably grow something like elodea or java moss easily.
As for ghost shrimp, it really all depends on the betta. I bought 4 ghost shrimp for a 3g betta tank, and they were all at least half-eaten 12hrs later. This was a particularly vicious betta, though (he tried to jump out of the water and attack me when I fed him
One last thing: How warm does is your office? Bettas dont tend to do well below about 74. I'd just be worried about it being in a small bowl without a heater.