Hello.
It sounds like the Maestro is a good choice for that kind of project. Each channel on the Maestro has three modes it can be configured in: Servo, Output, and Input. To use a button, you would configure the channel it is connected to in Input mode, and connect the button as shown in the “Attaching Servos and Peripherals” section of the Maestro user’s guide.
The Maestro has an operating voltage of 5-16V, so a good choice of power supply (if you want to power the Maestro and your servos from one supply) is a nominal 6V battery pack, which is also what most standard servos are rated for. We generally recommend a rechargable NiMH AA battery pack like these.
Triggering a voice (or any audio) and making the movements match will probably be the biggest challenge. The Maestro does not have any built-in support for this, but you might consider looking into the Visual Show Automation (VSA) program from Brookshire Software. This software is made for choreographing lights, animatronics, audio, and video and has some built-in support for the Maestro. There is a demo version available on the Brookshire Software website. Another option is to use something like the MP3 Trigger V24 from SparkFun or one of Adafruit’s Audio FX Mini Sound Boards to have the Maestro trigger the sound and time your servo movement appropriately. Both of those boards are able to trigger sounds from digital signals (e.g. connecting specific pins to ground) or through UART serial commands (which the Mini Maestro is capable of sending from a script).
Brandon