Break the Code

Can you decipher this code? Here's a hint: Z=A; +=1; ~=10. Enter the message in the space below. Try to figure out the code without using the decryption tool for every letter. Can you think of a faster or easier way to solve this puzzle?
=

GSV XVMGIZO
RMGVOORTVMXV ZTVMXB
DZH XIVZGVW RM
+=$& DSVM
KIVHRWVMG GIFNZM
HRTMVW GSV
MZGRLMZO HVXFIRG B ZXG
ENTER DECODED MESSAGE:
No need for a decoder. Just pick out every third letter!

WIGSAEPTNENECVRZNALTL
QIDXBOKJNTJORUVSFALON   PYIRTS
GFCAIOYUNNDSHLIWEDNKEQURCBEMHD
ROTFTHSIE   APFETAOPTHLHVJEXER
CJOAIF   XCMGKOEMDFZEPGRBAN
GHAFIMWEERURDKINYCCCALHN
ZOIQUNAVTORETLLUNLEWISKGIBEAGNSPCITE
TAGBRAYMTVWHQIEPFRGWIPVNBZG
ENTER DECODED MESSAGE:
Can you decipher this code? Here's a hint: 11 = A; 10 = Z. Enter the message in the space below.
=

41815 13 19 11 
19 3 22 25 13 11 4 15 14
19 24 22 11 24 17 22 159, 
6 11 
ENTER DECODED MESSAGE:
Can you unscramble this message?

(Hints: The numbers in the sentence are correct; all other words are scrambled. The answer begins with "THE" and ends with "DC").

 
HET SFRIT ICA QSTUDHERAEAR DGILIBUN NI 1947 SWA
CEDTOLA TA 2430 E ERTSET, WN NI NOTWHAGSNI, CD
 
ENTER DECODED MESSAGE:

- .... .   ..-. --- ..- .-.  
-.. .. .-. . -.-. - --- .-. .- - . ...  
--- ..-.   - .... .   -.-. .. .-   .- .-. .  
- .... .   -. -.-. ... --..--   -.. .. --..--  
-.. ... --..--   .- -. -..   -.. ... & - .-.-.-
ENTER DECODED MESSAGE:
OSS Director General Donovan has asked you to decipher the Enigma code machine’s message. Can you complete this mission?
=

15 3 4 9 6 16   24 20 4 19 15   24 13 4
23 24 20,   23 17 11   16 11 4 7 13 6 22  
3 22 11 15   13   14 9 21 17 11 4  
7 13 14 17 9 6 11   14 13 19 19 11 15  
23 17 11   11 6 9 16 7 13.   9 23  
14 20 3 19 15   22 11 6 15   13 6 15  
4 11 14 11 9 2 11   7 11 22 22 13 16 11 22
5 3 9 14 18 19 1   13 6 15  
22 11 14 4 11 23 19 1  
ENTER DECODED MESSAGE: