Thanks for your interest in KnownHost. We have many Reseller clients running WP based blogs KH Pro is our entry level plan but may suffice. If not you can easily upgrade to a larger plan. You should be okay but this really is tough to answer until the sites are actually on the server.
Resource limits with Reseller plans are simple - you can't use over 25% of the servers CPU for over 90 seconds or your in violation of our TOS/AUP. The rest of your limits are defined here https://www.knownhost.com/. This shows your disk space and bandwidth your alloted. In comparison to a VPS you don't get dedicated RAM so with a Reseller your sharing this with other users on the machine. Hope this helps.