I remember you Ethan, welcome back to bettas.
Everyone pretty much has most of your questions answered.
You can find the shelving at hardware stores. You are looking for shelves that can take a few hundred pounds per shelf. They are metal/wire they look like bakery shelves to me but offhand I don't remember what posts here had links to them. Maybe if you look on sites and ask here again once you find them? You can also use cinder blocks and 2x4 boards. I don't have links handy for that setup either but someone might. If you do cinder blocks count on a lot of added weight! You might consider setting them up on a cement foundation floor. I wouldn't set up in an upper story or an apartment. (2 10 gallon tanks plus enough cinder blocks to hold them came to close to 500 lbs if I remember right.)
If you are interested in IBC shows you should probably go ahead and join the IBC. I think the cheapest membership is around $15 per year for an adult. I am not sure what information is available to you in the IBC site but someone told me there is extensive information about genetics there.
I don't know if you need to belong to the IBC to participate in shows. Maybe someone can clarify on that too.