1. Yes
2. Larger than original. Possibly the smallest new LT tire you'll find.
3. good luck finding them.
4.A Series 1 is very light so tire won't wear very fast. Go with radials, not bias and they will last longer, handle better and give smoother ride. Because of the light vehicle and to fit the other criteria you mention, get a "Winter" rated tire. (Has the snowflake insignia on it.) Has a softer rubber compound for traction and plenty of siping for wet and ice/snow traction. Avalance by Hurcules 215 85 16 is one of many.
5. tread depth is measured in 32nd inch increments and a new tire is anywhere from 15 to 19 (32nd's). Go to the tire manufactures website and look up specs for the tire you're looking at. They will list tread depth.
6. Limestone, see other posting.
7.Ditto.
8. Land Rover only came in one colour in the SWB in those days IIRC. I don't recall the name and it isn't on the paint code file previously sent to you. Find a good example of it on an untouched panel, like a dash panel, and take it to a paint shop or automotive store and they can computer match it for you. Have you got a Cloverdale Paint shop or is that just a BC store?
9.Auto parts store or wrecking yard. Bosch or Hella or Cebie. Hella cost about $120 a pair new at Canadian Tire they have an H4 bulb and are the same as stock wattage and give you a flat beam low beam and awesome highbeam. Fit in like a stock headlight with nothing to change.
10.Hot Rod shop. You're on your own unless someone else can advise.
11. Yes, by all accounts. Make sure it's filled with oil and check it weekly, it might be worn. There is a guy in the southern states that makes and sells new parts for them. (Rovers Down South?)
12.Look at
Wise Owl Innovations Incorporated - Land Rover Parts check under Body Panels and Fittings and look for the Upper Seatbelt Mount. Wise Owl is just down the road from you IIRC.
13.Probably not but people do it anyways. What condition is yours in now? What's wrong with the stock trailer hitch mount that is on it now?
14.Generally considered to be no greater than half your vehicle weight, so about 1500#
15.Birmabright? Yes. Translucent green stuff, it's too late at night right now for me to think of the name. (zincchromate primer??)
16.Not Canadian tire. They used to have them for about $8. Commonly available in the US. Buddy of mine is looking for one for him and me; mine is worn out and is an excellent addition.
17.Depends were the leak it. O rings or paper gasket, if it isn't the O ring, use Permatex blue silicone gasket maker.
18.Hasp and padlock. or Series 2 door latches with locks.
19.Once the moss gets wet it slide easily. Oh! You live in Alberta; it doesn't get wet there. Go to an automotive glass shop and they can source similar window track. (or go to Wise Owl for the ones they sell for just your application.)
20.All of the things you ask about have been done. Have you wandered over and talked to the guys at Wise Owl? It isn't everyone that lives in the town where an international supplier of Series Land Rover parts is located.