Hide Products and Categories (Wholesale, club sales, etc.)

I know there is a way to create a customer discount group. But, it would be great if a customer could request to become a part of a certain group (ie. retailer asking to buy wholesale). We should be able to respond back with a welcome note or a we need this information note... And it would be great if we could only allow certain groups to view the items to purchase (maybe they are unbundled, used, special items, sell outs, bulk sales, one of a kinds... whatever ....we only want that group to see that item as opposed to selling it to the public.... this a situation I have now and the only solution I can think of is a 2nd website :no:). And it would be great if we could have categories that could only be seen by a certain group.... maybe that is where we can give more information about our policies for that group (we might want the hidden items to be in the normal categories but not available for everyday shoppers). I would say that to view the product you would need a special key unique to a customer to access that page.... not just the product id. We don't want spiders or lookers finding what we have hidden.