How many dice can you commit in one round? Is it one per action? Or can I commit two dice for "Sense" Defence and one for Suppress (if I have the ability to use it as an incidental)? Or would it take three rounds to commit them all?

As far as I know commiting dice is an action just like all other force power activations are an action, unless specified otherwise.

If it specifically states that you can Suppress as an incidental, then you can do just that, seeing as an incidental is not an action nor a maneuver.

You can find the answers to your question in the FFG Developer Answered Questions thread. Basically, for a single ongoing effect you can commit as many force dice as you like for one action, unless the power specifies sth. else. E.g. you can commit 3 dice in one action on the "Enhance Control: Agility" - Upgrade, boosting your Agility from 3 to 6.

If a force power has more than one ongoing effect (e.g. sense) you need a separate action to activate each effect.

If the power allows you to commit dice as an incidental, then of course you don't need an action or maneuver.

May the force-dice be with you

Fred