Connecting buildings with fiber

This will probably be a long post so bear with me. Our ISP wanted an obscene amount of money to run service to our house. So instead, we had them put the service in a outbuilding at the bottom of our hill. We currently have power in the outbuilding along with Spectrum's modem/router. Right now we are getting it up the hill with a Ubiquiti point to point and distributing it to other buildings via point to points using an PoE switch. It works ok but we just can't get the speeds we are paying for and along with other reasons (lightning, multiple failure points), I want to try another future proof solution....

My idea is to run fiber through conduit 800 ft from the outbuilding (building A) to building B. From there I want to run fiber from building B to building C, and again from building B to building D. I understand this is a fairly large undertaking and will be more expensive than what the average person wants to spend on getting internet to their house...and I'm ok with that. What I need help with is what networking materials do I actually need? I'm trying to understand multi mode vs single mode, LC vs SC connecters, and so on. Is there a way to explain this in simple terms so I can buy what I need and know it will work?