Welcome!
Sure, there are several ways to do that, but the most important thing to know is that any device which talks to the smartthings hub can then be used to trigger multiple other messages to other devices that talk to the smartthings hub. So you can have any switch or button which is controlled by the hub then trigger events on any of your other smartthings – controlled devices. 
There’s a how to article in the community – created wiki on how to group lights which will show you one way to do this, and mentions a couple of others.
http://thingsthataresmart.wiki/index.php?title=How_to_Group_Lights_Together
As far as extra buttons and switches, again there are a lot of choices. You might take a look at the buttons FAQ for some ideas: