I use Zoom at work. For reference, I am an EPIK teacher in the public school systems. At the beginning of the school year, I was at an elementary school. I didn't use Zoom there, but while I was there I taught and after school high school program that is offered for vocational high school students in my city, and I used then. At that time, I just had a free account and the lessons were two classes that were 30 minutes each, so I would simply do the lesson, have a break, and then start a new lesson or meeting. I didn't know much about Zoom at that time, so I would schedule meetings for each lesson, so each meeting had a unique ID and password. I would send that information to the Group Kakao chat that the supervisor of this program made for my class.
In the summer, I transferred to the teacher's training center in my city. The center is in charge of the after school program that I was doing, but because we do so many other programs here, I had to quit that after school program. It was around that time they bought a license for the after school teachers and the GETs (guest English teachers ... which I think is what we are called on EPIK?) that are at the center. Since transferring here, I have done Zoom lessons with middle school, high school, and Korean English teacher lessons. We are doing a program with principals and admin staff on Zoom this week! The GETs here don't schedule separate meets for their lessons like I was doing for the after school program. They just give their room ID and password and then the lesson starts they open their room. I do that now too. It is easier because then you don't have to schedule multiple meetings with different passwords each time. Also, it's easier for our supervisors that are in charge of the programs we do to keep that information because they are the ones who usually give it to the students.
If you want to do it that way, go to your profile and you will see your personal meeting ID. That is the ID for your room. Then you can see your password. All of as GETs changed ours to something easy (mine is 1234 ... haha!). When it's time for class I go to meetings, then select the personal room tab and there is a start button and that is how to open the meeting room.
As far as your questions, I think to use Zoom the students do need an email address to sign up for it. PCs are optional. For the teacher's class I did the past two weeks, on Friday one of the teachers was driving to Busan, and on the Monday she was driving back during the lesson! (I know that isn't safe, but she just listed to the class ... ). Last week I had a teacher give a presentation from her phone while she was on the way to the hospital! The ideal situation is they use a PC though. It is easier. Usually if a student doesn't have a camera or a mic on their PC, they will join the Zoom on both their phone, for the camera and mic, and their PC and it works out fine. You have to be mindful if they are doing that if you use the breakout room feature because as the teacher you want to make sure you are sending both their phone and PC to the same breakout room!
As far as your other questions. If you go the route of just sending your personal room information in lieu of scheduling separate meetings for each class (and I recommend using your personal room because it is so much easier for you, HOWEVER, by doing it this way, you run the risk of students from other classes joining your class because they have your ID and pass code. I have never had a students from the wrong class join personal room when I was teaching another class though), next to the start button there is a button to copy the invitation to join your room. You can email that to your students, but since it is not a schedule meeting, make sure you include in your email what time your class begins. If they sign on before you open your room, they will just be put in what Zoom calls a waiting room. Zoom usually will send you an email if someone is in your waiting room.
Zoom has different license and payment plans, so it is up to your school which one they would want to choose. You could get away with the free version if your classes are short, but it is easier having a paid version.
As others have said, you can Google how to do things are Zoom. There are plenty of tutorials out there. Zoom isn't too hard to learn. I haven't used all of the features yet, but if I need to learn something new I just Google it.
