Which e Commerce Platform Should I Use?

We have decided to start a new business and we are trying to determine which e commerce platform to use. Below is what we need it to do and what we are using it for, I would really appreciate any assistance on what we should use.

We have 2 separate companies we want to set up:

Company 1:
35-40 Skus
10 White Hat Domains (Domains which we are using white hat SEO)
10 Black hat domains (Using a lot of spam to get these ranked quicker)

Company 2:
800 Skus (lots of clothing items that is why the large amount of Skus)
6 White Hat Domains (Domains which we are using white hat SEO)
10 Black hat domains (Using a lot of spam to get these ranked quicker)

In both companies we want the following:
1. Want all domains inventory tied together, so if someone buys a product on site 1, sites 2-20 all show loss in inventory.
2. Want to be able to tie it into a fulfillment center.
3. We will try to keep the black hats and white hats site separate but want to keep the same shopping cart on both to control inventory. We don’t want the negative SEO from black hat sites to affect the white hat sites.
4. Want each to have it's own shopping cart so if you are on domain123 and check out, it should look like you are checking out at domain123 and not the main site.
5. Want to be able to expand internationally in the future and have geo targeted sites so if someone from UK logs in, it shows them inventory from UK and not US on each domain. I assume this will be a plug in of some sort.
6. Want to be able to use themes, which are available.

Thanks for any help,
Scott