I am new to the sport like you, and also in Florida, but our racing scene here is great as far as comrodery goes. I literally went to my local track one race day, walked around the paddock, and everyone was approachable. Clearly picking the right time to approach is key also. I saw a group doing an axle swap, so I figured then was a bad time to talk to them.
Also if you are like me with that dear in headlights look, they all seemed to know I was new to the scene if you will.
Expense from what I hear, is all dependent on how far, and competitive you want to be. You can do the bare essentials to get by with just racing, but you will see it in your results I feel. Or you can treat this as your own race team and go all out. Same with any hobby though the biggest expense is the initial plunge. I have heard from everyone running at my local track that Rotax is the cheapest overall after the initial plunge.
Others argue shifter is cheaper after the initial, or leopard. I believe it is as expensive as you make it. If you want a new chassis every year, a fresh rebuild every so many races, clearly this will be more expensive, but you will also see more consistancy.
Shifter curve seems so great because it is the closest thing to an F1 car as you will get iwth a kart. You have a hand clutch for initial first gear, you also have front brakes as well as the one on the rear axle. A 6 speed tranny that you have to manually shift 20-30x a lap, all while trying to hit the perfect mark, and be in the right gear.