A new live TV internet studio

I have been given clearance to produce a live internet streaming TV show and am the executive producer. The host has asked me for a list of necessary components while using a three camera shot. The show will be live for four hours and we need graphics and a switcher to change camera shots. We will be taking live phone calls and I have a nice Telos system for that. If I purchase the Blackmagic Design ATEM Television Studio Production Switcher, what else will I need? Do I need a sound mixer (Mackie ProFX12) and main control board (Audioarts R55E 8 Channel On Air Console R-55e-8)?