Andy
Bob gave a guide to building a split hull earlier on in this discussion, you basically choose a mid point frame in the hull and instead of fitting the frame you create two full height bulkheads, the hull is split at this point for transport and is bolted together when you get to the lake.
The superstructure, which is usually a lot shorter than the hull can be a single piece, which in usual practise is separate from the hull, or split in a similar manner to the hull (although the bulkheads don't have to be watertight)
The turrets being electric can be connected at the bulkhead split point with a simple plug/socket arrangement.
The confidence to build a big model come with experience but I can say that there is no skill difference between building a 4ft model and building an 8ft model. The difference in skill level occurs at about 10ft after which the model requires the extra structural strength to support its own weight.
I hope this helps explain.
Paul