S
No, only after a full stop (period). Also do not capitalise "The" and "A" in your sentence.
Capitalize areas of the country, but not directions. My answer would be yes, capitalize it. Capitalization is a sign of respect. If it is wrong on a worksheet you will lose a point (and don't argue because the old school textbook (1985) doesn't capitalize it in the answer key). But if you don't capitalize it in a paper or web site, you could hurt someone's feelings.
Yes, it is a proper noun, referring to a constellation and also to a star sign.
No. When simply referring to a podiatrist, there is no need to capitalise it. It would be capitalised if it was part of a title on a sign, such as "T.M.Smith, Podiatrist".
Saturday (always capitalize the "s")
8 Sides on a Stop Signsides on a stop sign
8 Sides on a Stop Signsides on a stop sign
8 sides on the Stop sign
8 Sides on a Stop Sign
8 sides on a stop sign
8 = sides on a stop sign
8 sides on a stop sign
Eight sides on a stop sign. (in the UK)
No, "sign language" is not typically capitalized in a sentence unless it is part of a title or at the beginning of a sentence.
8 Sails on a Sailing Ship8 Sides on a Stop Sign
8 Sides on a Stop Sign 8 sails on a sailing ship.
8 Sides on a Stop sign 8 Sheep on a Sheep Sheep =D PwwNage!