Storing Tobacco Questions

Thats what we call mason jars...theirs nothing wromg with storing it in a mason jar. It creates a tight seal and keeps items fresh. Thats my opinion but i know that you will receive an abundance of helpful info coming soon.

1. A lot of pipe smokers cellar their tobacco because they are hedging against future price increases (thus have no plans for immediate consumption) or because they desire to age the blend. This additional maturation encourages a general improvement of the tobacco - marrying flavours and allowing additional fermentation processes to take place that round out a blend. In general, latakia softens and burleys mellow and virginias sweeten with time...
The reason they take the tobacco out of the original tins is because some tins just aren't suited for long term storage because they a) have no seal to begin with b) have lost their seals during the shipping/handling process. A tobacco that is well suited to aging (such as a VA flake) should last indefinitely when stored in a clean mason jar - if left uninterrupted for a period of years, the microbial processes of aging will take place and you will have a "different" tobacco on your hands. Most people agree that an aged blend is better, but there are plenty of exceptions - plus there is no accounting for taste.
2. Aromatic tobaccos fade fast. Within a year, to my tastes, most of the flavouring is gone - especially if you start out with a subtle aromatic. Cellaring/aging is not really suited for the aromatic smoker IMO. If you buy 2kg of a flavoured blend and leave it for a year or two, you will probably come back to a tasteless pile of leaves. Some people claim positive results with things such as 1Q which tend to last for quite a while, as well as Virginia based tobaccos such as MacBaren Vanilla Cream or Dan Blue Note. Again, the flavours will be much milder as the casing wears off but the increased sweetness of the VAs may make up for it to some degree... Honestly it is a crapshoot, but for my money I would never cellar aromatics on a large scale.
3. Some tins can rust (so can some jar covers) but I would think that comes from a high humidity environment or a lot of temperature changes that can create condensation over time... Keep a steady temperature and "normal" level of humidity and you should be fine. To err on the side of caution, keep them in a place shielded from sunlight such as a drawer, box, cooler, or closet and do not let them get hot. Cooler is better, but like I said you don't want swings...
4. Those Kilner jars are identical to what we refer to as Mason or Ball jars in North America. They are ideal for this purpose.
Props to roth, beat me to it!

Regarding #5, 250 ml jars should be your standard if you are jarring one tin at a time.
You will comfortably fit 50g of loose cut tobacco in there with some space at the top.
Flakes can be tricky - it all depends on the blend and the shape of the jars. You will probably be able to fit two tins of flakes in a tall 250 ml jar but there could be a few leftovers... Something like coincuts such as Luxury Bullseye Flake or Escudo will easily contain 100g in a 250 ml jar...
500ml and 1L are serious volumes of tobacco. I would not want to age too many things in jars of that size because of the sheer amount of tobacco you'd have to consume in a short span after opening. If the Kilner jars are not too expensive I would just get many small ones rather than fewer large ones!

I store mine a jar, but then for daily use I have a leather tobacco poach.

I also have a few questions to add to the discussion if you don't mind:
Is there any disadvantage to keeping baccy in zip lock bags? I currently have several baccys in 1oz volumes or less. That could get hard to stack with all those little bottles.
When you store them in Ball jars, do you just screw them closed as you would a jar of pickles, or do you do some kind of sealing as in a canning process?
How long does the baccy last after it is re-opened?

If you plan to smoke the tobacco soon, a few weeks to a month or two, then I find that a ziplock will hold the moisture just fine. But the thin plastic does allow some air in and out of the bag. That is why it is not very accomidating for long term storage.
The ball jars will have a rubber seal under the lid, so when you screw the cap on it will press against the rubber ring under the lid making an air tight seal. These jars are mostly used for long term storage and aren't frequently opened.
If you plan to open them once in a while then most people will use the glass jars with the metal clasps for easy access. Preferably with a mouth wide enough to easily fit your hand in.
And for the last question on whether or not it will last after it is re-opened? Of course it will. Why wouldn't it?
Here are the jars I use to store pipe tobacco in that I frequently open.