7D nails for supers and hive bodies (Galvanized vs hot dipped, vs electro-galvanized)

Just a quick answer for #2:

Stainless steel - typically most spendy, will likely outlast the wood they are placed in. If you want a 'show' hive this might be the way to go. Uneconomical otherwise.

Hot-dipped galvanized (HDG) - regular steel (also referred to as carbon steel or mild steel) that has been dipped in a bath of molten zinc, leaving a heavy coat of zinc on the surface. Zinc acts as a sacrificial coating; over time, rather than the steel rusting, the zinc does. The zinc just doesn't look bad when it rusts.

Electro-plated or electro-galvanized or zinc plated or zinc-electroplated - carbon steel that has been dipped in a bath containing zinc ions. An electric current is passed through the metal, which chemically deposits zinc on the surface. The same effect as hot-dipped galvanized, but the coating looks better and lasts half as long (or less).

Cement coated - carbon steel coated with a non-corroding material. Works great when the coating is intact. . .

Aluminum - not as corrosive as steel, but will still 'rust' given enough time. Spendy, and difficult to hammer in without bending - the material is typically softer.

Bottom line - HDG is probably the best matched material for the life of the wood they are hammered into. Cheaper than stainless, but last longer than others. Other than the issues of finding 7d, readily available.

Sizes of nails, for US
The size of a nail is determined by its length. In some types a definite relationship exists between the length and the diameter of the shank. To illustrate this point, examine a 2" common wire nail, a 2" casing nail, and a 2" finishing nail. It will be found that the wire nail is made of 11-1/2-gage wire, the casing nail of 12-1/2-gage wire, and the finishing nail of 13-gage wire. While all three are the same length they are of different diameters, the common wire nail being the thickest and the finishing nail the thinnest.

In the United States, the length of a nail is designated by its penny size, written with a number and the abbreviation d for penny; for example, 10d for a ten-penny nail. A larger number indicates a longer nail, shown in the table below. Nails under 1¼ inch, often called brads, are sold mostly in small packages with only a length designation or with length and wire gauge designations; for example, 1" 18 ga or 3/4" 16 ga.
Penny sizes originally referred to the price for a hundred nails in England in the 15th century: the larger the nail, the higher the cost per hundred. The system remained in use in England into the 20th century, but is obsolete there today. The d is an abbreviation for denarius, a Roman coin similar to a penny; this was the abbreviation for a penny in the UK before decimalisation.
penny size/length(inches)
2d 1
3d 1¼
4d 1½
5d 1¾
6d 2
7d 2¼
8d 2½
9d 2¾
10d 3
12d 3¼
16d 3½
20d 4
30d 4½
40d 5
50d 5½
60d 6

See Below for Gauge/Length Relationship for Wire Nails (Not Casing or Finishing)

When looking for nails most people get that the penny size refers the length of the nails. but you also run into type of nail. Sinker, Common, Box, Joist Hanger, Concrete etc. Each of these have specific uses with different pluses and minuses. I use a 6d galvanized box nail for hive boxes. A box nail has a thinner diameter to help prevent splitting of the wood when nailing into the edge of a board. They also bend easier when driving them. Galvanized to prevent rust but they will also discolor the wood. Stainless steel is used to prevent the discoloring when you still want rust prevention. I use 6d galvanized ring shank nails to build fences. If I got them for making boxes and hand driving I woudl get yelled at those who are doing the assembly. they are even harder to drive. but they hold stronger usually. Your wood needs to be stable for them to work well.

At any rate I would find 6d galvanized box nails or as close to it as you can readily find. IF all you can find is common then pre drill. This does the same thing as a box nail would afford and you have a stronger nail that is easier to drive.

You then have the various methods of galvanizing. some work better than other. the main thing is you do not want to pay for higher priced coatings than you need and still have a coating that stays on the nail. I like hot dipped myself.