Land Rover axles have a little tube or in the case of older ones a brass bell shaped object screwed into the top. This is the breather. The idea is to relive pressure in the axle when operating, most 4x4 axles have them. The older type can get bunged up with muck, they are just a ball bearing and spring, so it advisable every so often to remove and clean. The newer Landy's have a simple plastic pipe going from the axle up to some part of the chassis, these are known as remote breathers. The down side of these is they can get snapped short allowing muck or water into the axle or crimp and create over pressure. Have a look whilist it is the workshop and if you have the old type consider changing to a remote set. Often overlooked but important.
Depending where you are based there are quite a lot of specalist landy dealers /restorers who have second hand bits. Local clubs are also useful for bits and help, always ready to 'Green' another lost soul. If you are starting totally from scratch, investin decent tools, cheap tools= damaged parts, lots of frustation and the job dosen't get done. I'd suggest the Halford's Advanced range, not the cheapest, but not as eye watering as brands such as Snap on, I use mine on everything from cars to the dodges and Land Rovers, never managed to breack them yet. If the locks turn out ok afte twiddling, you can buy cheaply a set of new barrels and keys, these will also fit second hand locks.