Will it last in a wooden box at room temp for at least 5 years, or must it be frozen long term?
Freezing only helps to slow down the molecules movement and therefore slow down the nicotine reacting with the available free oxygen. The question is how much potency are you willing to sacrifice and whether you mind/want extra bite/
throat hit/pepperiness. How much has already been discussed at length in other
threads. Take some time to read and decide what is acceptable for you.
From what you have already described about your storage:
--In the dark... Good.
--In glass... Good.
--In a wide-mouthed mason jar... there are better options.
The problem with using a wide-mouthed container, like a mason jar, is that it exposes a greater surface area to the air also in the bottle. You could reduce this impact if you were to use something like a vacuum sealer to suck out as much air as you can, or use an inert gas like CO2, or argon to displace the air (so there is no oxygen to react with).
This is why most choose to use a bottle with a tapered neck/opening and fill it to within about a1/2 to 3/4 of an inch of the top minimizing the amount of air (head-space) left in the bottle. (Keep in mind, too large a bottle that is only partially full, will create the same problem as using a mason jar.)(Also, don't fill ANY container clear to the brim, or you may experience overflow upon opening, if the temperature is warmer than it was at the time of bottling.)
As for using your leaky nic; unless you are concerned that someone maliciously tampered with it, I would think it would be to use.