Large format is a broad subject and research before purchases is the best idea. Landscape photography can also be wide ranging and have a very personal approach. To weigh in on your questions:
1. You might consider a general purpose lens that will cover your format and permit movements available with your camera and bellows extension. I went with a 210mm -- slightly longer than the 50mm for you 35mm camera. If drilling your own lens boards be sure you can do it accurately and dead center.
2. I would start out with 400 ISO film such as Ilford HP5.
3. I use old Kodak hard rubber tanks that last a lifetime if you can find some. the film is held in individual frames and not touched until perfectly dry.
4. Same chemistry as for other size film. ( my preferences are Ilford ID11 or Pyro PMK)
5. A spot meter.
6. Lisco film holders are generic and I would expect them to work. You might be able to find a roll film holder and practice with 120 film.
Happy New Year! Ihope this may have been of some help.