No - you can go to classes/jams alone or bring a friend!
In general: water bottle, clothes you feel comfortable being active/upside down in
Leefield jams: this space has sprung floor so no mat required
Outdoor/Gym jams: bring a yoga or panel mat
You could attend a class and get introduced to foundational postures/concepts. You could also do a private if committing to a class series doesn't work for you or if you want to learn at your own pace. This can be a nice route to get an introduction to not only the postures but safety principles like spotting.
You could attend a jam; although previous experience isn't necessary it can be helpful to have before attending jam. People are generally quite welcoming/friendly and willing to show basic skills, but recognizing that jams are unstructured spaces/no formal instruction and folks may have other things that they're wanting to work on.
No, you can build strength and flexibility over time with practice
Flyer: The person in the air/moving through poses while being lifted
Base: Providing foundation and support to the flyer
Spotter: Ensuring safety; they aren't directly taking part in the skill and their whole purpose is to be ready to help take the weight of the flyer or guide flyer safely to the ground
We encourage you to try all three!