Solution:

Heroine

Solution:

The letter 'n'.

wiNdow - widow
door - doNor

Solution:

They're both in the middle of wa'T'er

Solution:

Typewriter

Solution:

The answer is C.

These are letter of the question asked in reverse order.

Solution:

Empty.

(mpt, emty or mt depending on your interpretation)

Solution:

Error

Solution:

N for November

M: March
A: April
M: May ....and so on ...

Solution:

An Envolope

Solution:

Princes (male and plural) add an 's' Princess (female and singular)