I think the easiest way to do the first task is to define a "mask" around the component. It's fairly easy to edit the mask and put a "popup" to define a list of values to select from.
The second one is do-able, too. You may take a look at the "Flow Rate Source (IL)" block, which is basically 4(?) blocks in one. There will be some additional work for sure. Another possibility, maybe easier, is a variant subsystem that contains two versions of the Simscape component.