Mold release wax, and PVA (polyvinyl alcohol) for release. 2 layers of 4 oz. will probably be a good place to start. I really like a "crowfoot weave" or a "twill weave" because they drape, or take contours well. Be prepared for disappointments! Your first attempts won't be perfect. Study molding techniques, and part layup processes. Fiberglast Products has training videos on the net. I've been working in fiberglass for 40 years, and I still make mistakes, and I'm still learning. Thayercraft is a good source for cloth. I just got about 30 yards from Steve last week.
Most modelers split their airplanes vertically. That's what I've always done. That doesn't mean that for your project you can't split it horizontally. It's your choice. Keep in mind the "draft of the part". You don't want it to lock up in the mold. A lap seam is a great way to join the part halves, but it requires more mold preparation up front. It pays off in the long run if you are producing a lot of fuselages, but not so much if you only plan to make one, or a couple of parts. The alternative to a lap seam, and the most common way of joining parts, is with joint tape. In a production environment it's beneficial to join the halves in the mold, which requires access to the inside of the part through the mold (typically the wing saddle) and special tools. The parts can also be joined outside the mold. I tape them together, or spot glue with CA, and then tape the seams internally. Good luck, and let us know how it turns out.