The possessive is cannabis's. Here' the guidance:

SINGULAR COMMON NOUNS ENDING IN S: Add ’s: the hostess’s invitation, the hostess’s seat; the witness’s answer, the witness’s story. (A change from previous guidance calling for just an apostrophe if the next word begins with s.)

Dunkin's rewards program.

There's not necessarily a 100% right or wrong in these usages. As noted in the hyphen entry, much of hyphen use is a judgment call. I've amended the April 18 answer to conform, deleting the hyphens when not used as a modifier before the noun.

Best to be specific and use the day as well as the month and the year. Also, do you mean the day it was written, or the day it was published? Often there's a gap!

It's the Democratic Party.

It's typically spelled out as you have it. That's not consistent with the fact that United States is typically abbreviated in such a use: the U.S. Department of Treasury. But that's what usage and our style is for both.

Yes.

Either is fine. Depends on what you want with the rhythm of the sentence. Adding the comma puts a bit more emphasis on too. But it's largely a matter of preference and what sounds right to the ear as you read that sentence and the surrounding sentences.

I'd use the hyphen in both cases. Definitely as a modifier before the noun: These are individually quick-frozen shrimp. (Without the hyphen, it could read as if the frozen shrimp are quick individually, a thought that is entertaining me greatly. I'd like to see it animated.)

After the verb, it's not as necessary. But I think adding the hyphen helps with clarity there as well.

The first is fine, if you absolutely must. As for the second (and really, the first as well): I'm going to answer that with the following parts of hyphen guidance, again. That is the answer. We would not sanction writing it the way you have it, regardless of how it's punctuated.

From the entry, this paragraph and the second sentence of the second paragraph:

If the sheer number of hyphens in a phrase, or confusion about how to use them, can daunt either the writer or the reader, try rephrasing. It’s a guide about how to use hyphens wisely, not it’s a how-to-use-hyphens-wisely guide.

Generally, also use a hyphen in modifiers of three or more words: a know-it-all attitude, black-and-white photography, a sink-or-swim moment, a win-at-all-costs approach. Consider carefully, though, before deciding to use more than three modifiers.

The hyphen is optional, but I'd say no. It's clear without a hyphen, right?

It's definitely not one word.

No, we wouldn't capitalize that. 

That's largely correct  as of now, but it should be seven to 10 days. And as we discuss our numbers guidelines with an eye to possible revisions: What do you and others think of our guidelines in general, and sentences such as this?

If moving calves to the auto feeder before 14 days, feed 2 quarts, three times a day or 3 quarts, two times a day for seven to 10 days.

It's commonly done that way. That's really the best rationale I have. Just as my employer's name is The Associated Press, but we say: Associated Press spokeswoman Lauren Easton said ...

But: Francesca Fernandez, spokesperson for The Amsterdam Hotel, said ...

Here's the multi- entry:

multi-  The rules in prefixes apply, but in general, no hyphen. Some examples: multicolored multimillion multilateral multimillionaire 

So: multitrillion-dollar question

If it's widely known as the Special Masters Committee, we'd likely keep the capitalization. Our existing guidance isn't entirely clear and is under review. We may tweak it next year.

We've discussed and decided to go with Crown of Thorns.

No period there. 

Do it as you describe here.

The comma is optional. You don't need it. The quote marks are optional too, in this case, but I'd use them. 

It's pre-Civil War.

Yes, I'd hyphenate it. It could initially be read differently without the hyphen, as if the benefits or the chickens are freeing a range. 

I'd make it as you have it:  An at-will associate; the company's policy of employment at will.

I'd use the hyphen.

We use it in those cases.