No.
Yes, "Special Forces" should be capitalized when referring to a specific group, such as the United States Army Special Forces, in a sentence.
The scientific or taxonomic name would be Rosa 'Dynastic Carefree Wonder'.
If you are referring to the U.S. Army and Air Force reserves, yes, they are known as the "National Guard." Actually U.S. Army Reserve and Air Force Reserve are federal reserve forces. Air and Army National Guard are state forces that can be federalized by the President.
No, but if you named the purple amethyst Shelly, then it would be capitalized.
No, first frost would not be capitalized
Yes, it would be capitalized
Son of Heaven
No unless it is at the beginng of the sentence
No it shouldn't be capitalized.
Yes, Siamese would be capitalized.
Yes, PC would be capitalized.
They are not proper nouns. They would not be capitalized in a sentence.