Not uncommon. Caused by the rim lettering which is a separate process.
If you look at the rim, you will probably see that wherever their is a raised part, you will find that a letter has been stamped in that area. Too heavy of a stamping pushes the metal up. ( It has to have someplace to go)

Agree with Bill. It is partially grease filled die.
Also it is a 1906, not a 1905 as per your heading.

I would grade it at AU from pictures supplied.

That dot is actually a die chip that for some reason has some premium attached to it
depending on grade. It is known as a 1958 dot but is not rare.
Hard to grade your coin with the pictures supplied as the Obverse has too much glare.

The 1944 is just heavily damaged. Don't see any errors.
The 1956 looks like it may have a slight lamination.
In the future, please post pictures of the full coin instead of in sections.
It makes it easier to diagnose.

They don't all have Die Cracks but it is not uncommon to have them.

It's not a Double Strike or you would be seeing the devices of the second strike somewhere. Hard to tell from a picture but it looks to me like it may be something like glue on it. Try soaking it in acetone for 24 hours and see what happens. Whatever it is, it is something that could not have happen...

I have seen that once before. Not sure if it was the same coin or a different one.
Anyhow, whatever or whoever caused it, was done after the coin was minted
so it is not an error. Maybe someone was trying to create their own "Poppy Coin"

If it is on the ship side, that is the Reverse. The Obverse has the queens bust on it.
Can you show a picture, there should be no beads on a 1949 Silver Dollar. As far as I know, they
didn't start using beads instead of denticles until 1965.

Hard to say for sure when you only show part of the coin but the bubble could have been caused
by heat which expanded the air between the copper and nickel.

That is only .17g overweight, certainly not much.
Not quit sure what the Canadian tolerance is for a Quarter but in the US it is .19g which
would make it within tolerance.

It's to commemorate one of Canada's top three moments in the winter Olympics by winning the gold
in both Men's and Women's Hockey. The third was in 2006 when Cindy Klassen won the gold in speed skating.

Prefix EHF and EHC are part of the same series so the values would be the same.

NH1 SW

They were all a small date in 1937. In 1938 they increased the size.
If you are going to compare coins, make sure you compare coins of
the same year as the dies sometimes change slightly from year to year.