How do I change the objects dynamically in HoloLens ?

I'm a complete beginner to Unity and HoloLens.

My project has to do with OpenNLP package c# where i tokenize the string into words and show hand signs for each word.

I have some doubts in this regard.

1. Our input is voice (sentence). How/Where do i write the code for accepting the input?
2. I want to make a game Object and dynamically change the object to show different hand signs. Is there any more efficient way to do it? If not, how do i implement it?
3. How do I make use of OpenNLP in HoloLens? I mean is it already installed or do we need to install tools? How do I install them?

Sorry if some/all of the questions sound stupid. I'm completely new to this.
I hope you can give me some pointers? Any tips, resources are greatly appreciated.

Thanks people.