To solve the ciphers,
notice that there is an unusual hyphen in the comment from the poser: "All you'll need lies within the puzzle. Cross-words are cool aren't they?". In conjunction with the
anagram tag, this hyphen clues us to the fact that we should look at anagrams of the cross letters. This yields FIRST LETTERS.
as Deusovi notes, taking first letters from the down clues we get CLSENIE, which anagrams to SILENCE; and from the across clues we get TJRPUIE, which anagrams to JUPITER.
Applying these to the first and second ciphers respectively yields:
While your code has helped you figure this message out, there is one final test for you to resolve. Check the second message with your second code.
I am the thing you seek, the treasure you desire, the end of this puzzle. What am I?
(M Oehm decrypted these using analysis.)
The solution to this riddle is:
ANSWER or SOLUTION
Some of the cluing was bit unfair, in my opinion. Answers like "dietary", "expenditure" and "lavish" violate the constraint that definitions agree grammatically with the words they are cluing; "Cool numbers that like the number 1" doesn't make much sense as a clue for "primary"; assuming 11 is correct, "in a raging frenzy" may not be an established enough construction to warrant a missing-word clue (although it does have some currency); and, assuming "serendipitous" is correct, the definition is a bit loose. I would recommend using more checked letters in future crosswords as well as adhering to the grammatical agreement rule in clues.
The first cipher is a bit superfluous: It tells you to use a keyword that you already have on ciphertext that is already available to you.