It's a bolt-on neck, so it's easy enough to put on and take off. Fit a capo on the neck on a lower fret, or even just put some tape round it, slacken the strings, then you can undo the screws and remove the neck without having to fully remove the strings. Put the neck back on in reverse order. It's something you get used to doing if you've got a Strat or Tele with a heel-end truss rod adjustment.

Just make sure that the neck mounting holes in the body are drilled out to just the right size to fit the screws through without binding. This allows the screws to fully pull the neck down to the body. It's also the way that any holes for screws joining two pieces of wood together should be drilled.

You'll certainly want to fit the scratchplate before fitting the neck, but scratchplate fitting isn't as easy as it may seem, as the pots and output jack are fitted to the plate (which is easy), but the pickup wires need to be fitted through the holes in the body to the control cavity, meaning that they have to be soldered on in situ. It's awkward but you can do it. Alternatively, as it will all be covered by the scratchplate, you could rout out (or chisel or just drill out using multiple holes) a channel to run the pickup wires in, so you can pre-wire the scratchplate (with the exception of the output jack).

Tung Oil, Danish Oil, TruOil, Boiled Linseed Oil. All polymerising oils used for guitar finishes, especially necks. There will be some slight differences between them (though they are all variations on a theme), but they will all give a similar finish, and wear can be patched up by the simple application of more oil in the future.