There are two whitelisting mechanisms. One is using the Proxy (perhaps with the content filter) and the other is gateway management. The Proxy can be set up in transparent mode but is not very effective like this as it does not filter any https traffic, and a lot of traffic these days is https. The other way is to set it up in non-transparent mode with or without authentication. If this mode you need to explicitly set up every device to use it or use Web Proxy Auto-Discovery (WPAD). There is a HowTo covering how to set it up, but not what to put in the wpad.dat file. The proxy is relatively resource intensive and some applications just don't work with it. The alternative is Gateway Management. This is effectively a DNS solution and is very powerful and light weight on resources but is most effective with the paid versions.

For speed limiting, we do not really have an app. We have a Bandwidth/QoS app which prioritises traffic rather than imposing specific limits. This means that, for example, if there is only low priority traffic, it can take all the bandwidth, but has soon as there is higher priority traffic, the low priority traffic starts getting limited.

I believe, if you read the /etc/clearos/qos.conf file, that you can achieve some limiting by manually tweaking some parameters.