I'm currently using "Values to be selected from a list", and "Category", with List type being Checkboxes.
My Categories list has 5 items in them, I'd like to have 3 of them selected by default (as 3 of them are commonly used).
I seem to be only be able to select one of the Keywords as my default, is there any way to have more than one selected?
I'm on Tridion 8.5
Sorry to dissapoint you but no. Default value is only one, and its so by design of product.
The default value which can be set on Component creation is only a single value. If you need multiple values, you can use an event handler to set additional default values.
Please keep in mind you need to set these only once so you need to choose the correct event and do some checks if this is indeed the moment to load defaults.
There used to be a TOM event named OnSchemaGetInstanceDataPost, I believe this was the Schema being read for the initial creation of a Component, the documentation (https://docs.sdl.com/LiveContent/content/en-US/SDL%20Web-v5/GUID-DF367267-7648-4137-BBAB-C9FF14D28D11) states that in the .NET event handlers this event trigger does not exist. But you can approximate it by the combination of the Subject Component, the Type SaveEventArgs and the Phase Initiated. So that is a nudge in the richt direction, maybe somebody else in the community can add a more detailed answer.
