You are clearly have no or very little experience of racing pigeon, so first off welcome to a wonderful sport and good luck, I would recommend racing natural to start with, this is when you pair the birds up and rear a round of young birds and race them sitting on eggs etc. This system will allow you to observe and learn all about the birds behavior and all aspects of housekeeping and general loft management, then you could look at other racing systems, good luck. As for the loft one larger section for breeding and one for young birds, a third for storing corn etc is optional.