Solution:

BACK

All the others can also be read backwards as proper words.

Solution:

61

Reversed digits of squares of number in descending order.

Solution:

Submarine

Solution:

3211000

Solution:

Each word has 3 consecutive letters of the alphabet-
couGHIng (GHI)
thiRSTy (RST)
DEFiant (DEF)

Solution:

129.

These are the first 10 prime numbers (2, 3, 5...) prefixed with a 1

Solution:

SQRT(.2 ^ -2)

Take .2 and raise it to the power of -2 and then take the square root.

Solution:

HighJacking (High+Jack+King)

Solution:

128.

There are 62 squares of size 1x1.
There are 41 squares of size 2x2.
There are 18 squares of size 3x3.
There are 6 squares of size 4x4.
There is 1 square of size 5x5.

A total of 62 + 41 + 18 + 6 + 1 = 128.

Solution:

On a sailboat (sale boat).