I’m not sure about the WHMCS side of things. Unfortunately, we don’t directly support WHMCS. WHMCS would be the best point of contact regarding their product. Technical Support | WHMCS
You can have a reseller and a regular package named the same thing. I do not know how WHMCS handles that on their end, though. Typically, the reseller would only access the server via their API Key or login, which would be the defining factor. Not sure if WHMCS does that or just uses the server admin’s credentials.
Whether to use the same shared IP as your resellers is probably based on how much you trust your resellers. If you share an IP address and one of their customers has a spam issue, you may end up with your customer’s IP address on a blacklist. On the other hand, IPs aren’t free, so it may be more cost-effective to lump things together.
I’m not sure if your question about dedicated IPs is related to InterWorx or WHMCS, but a Dedicated IP (as defined by InterWorx) is an IP address that can only have one SiteWorx account on it. If you would like an IP address that is “dedicated” to a reseller, you’d just use a Shared IP and only give that one reseller access to that IP address. The only time you’d give a reseller access to a Dedicated IP is if they needed to provide one of their SiteWorx accounts with an IP that only that account can use (and no one else).
The “Server Admin” reseller (you) will always have access to all IP addresses, but Resellers will only be allowed to use the IPs they’ve been assigned:
In the screenshot above, I’ve only shared one Dedicated IP with this user, so they can only have a max of one SiteWorx account. If they wanted to add another, they would have no available IPv4 addresses on which to set up that account on.
I hope that helps clear up the difference between Dedicated and Shared IP addresses from the InterWorx perspective. All that to say, the overwhelming majority of your IPs will likely be set up as “Shared” IPs in InterWorx.