Hex numbers go 0 1 2 3 4 5 6 7 8 9 A B C D E F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F But after 9, what numerical values do the letters have? Is it going 10, 11, 12, 13, 14, 15, 10, 11, etc?

Yes, 0x0A (base 16) equals 10 (base 10)

Hex -> Decimal system conversion table:
A -> 10
B -> 11
C -> 12
D -> 13
E -> 14
F -> 15

But 10 in hexadecimal means (1 * 16 + 0)=16 in decimal system thus SIXTEEN.
The same for 11 in hexadecimal that is (1 * 16 + 1)=16 in decimal system thus SEVENTEEN.

In hexadecimal (and also in binary or octal systems) you should read each digt/letter by itself starting from left.
To convert hexadecimal values to decimal numbers you just have to sum all digits/letter multiplied each for a 16 factor (2 in binary, 8 in octal) power by position (0 is power of most right digit/letter, 1 is power of the second most right digit/letter and so on).

Thx alot. :D