Google has two ways to do video - personal video calls using Hangouts or Meet, and Live Streams. Hangouts/Meets are only viewable to the participants in the video call (maximum 25) and are not recorded. You would typically find these links in Google Calendar.
Live Streams (formerly known as Hangouts on Air) are like news broadcasts. You have a number of hosts/reporters who deliver the information (i.e. participants) and the viewers. As most of you will want to reach the largest number of viewers and retain a recorded archive afterwards, we'll focus on Live Streams.
Trying to run a broadcast and wear all the hats yourself can be a daunting task, especially if you're new to the platform. Instead, get some help (great opportunity for student involvement) to help with some of the tasks:
Host - keeps the show focused and on time.
Comment wrangler - monitors the chat, Q&A, Twitter, email, etc. Helpful in pointing out questions or when viewers aren't understanding what's going on.
Video switcher - chooses which video feed is broadcasted. Although Youtube will often look after this, sometimes you may want to override its decisions.
For the most part, cameras that come with recent monitors/laptops will do fine. However, if you're going to spend money, spend it on a decent audio headset. The microphone on your laptop will pick up all your typing and just sounds bad. Remember, you can always do a broadcast by just screen sharng slides, but if people can't hear or understand your, they will leave.