Hi Andy,
Magento's B2B feature set is relatively new, and only covers a few major features, so the good news is that the vast majority of really strong B2B sites built on Magento managed without these features. I'd consider Magento Commerce (EE)'s B2B to be an accelerator. It saves you from needing as many extensions and customizations, but it's not the only path, especially if budgets don't all for the paid license.
B2B sites are notoriously unique anyway. Each is a snowflake. Case in point, you've mentioned some functionality that may require or be enhanced by Magento Extensions (plugins). These include:
- Extensions for Customer Activation/Approval that will allow shoppers to sign up, but then wait in queue to be approved by an admin. https://marketplace.magento.com/catalogsearch/result/?q=approve#q=approve%20customer&idx=m2_cloud_pr...
- Quick Ordering by the shopper (by simply entering a SKU, or by uploading a CSV file): https://marketplace.magento.com/catalogsearch/result/?q=approve#q=quick%20order&idx=m2_cloud_prod_de...
Aside from extensions, some features can be handle natively. For instance, Magento Open Source (CE) includes "offline" payment methods like Purchase Order, Check / Money Order, and Cash on Delivery. While you can adjust what these payments methods are referred to as, they will allow shoppers to order online successfully without providing a credit card or other "online" payment.
In regards to selling quantities in packs, there are multiple ways to solve that need. Some of that comes down to how they handle product data in their other systems (ERP, etc.), and the customer experience that they'd like to provide. For instance, you can have a product that's sold as follows:
Product Name = Widget
SKU = Widget123
Minimum Quantity Allowed in Shopping Cart = 6
Quantity Increment = 6
Price = $2 per unit (so $12 minimum)
Price for 12 or more = $1.80 per unit
Price for 24 or more units = $1.50 per unit
etc.
(these are just examples of available settings)
Another option would be to offer this as a "pack":
Product Name = Widget 6 Pack
SKU = Widget123_6Pack
Price = $12
If possible, I'd recommend avoiding a random free template, and use the template provided by Magento. You should run into fewer conflicts, less risks of bad code, easier upgrades/maintenance, etc.
In regards to a multi-site, yes, you can run more than one site from a single install of Magento. Admins can login, and are granted access to the materials in the Magento Admin that you've granted them permission to. It is indeed one admin, so they'd have access to administrate both stores. It's relatively easy to set different payment and shipping methods and options for the two. What can be a bit trickier, is sharing SKUs between retail and wholesale stores (ie. Selling SKU=widget123 in both) There are some features that work well for this, like pricing and tiered discounts (Customer Group Pricing), and others that are trickier.
Best of luck!
