Always use the date your are writing the letter as the date of the letter. UNLESS, you are writing the letter on a date before when you will send the letter. In this case, use the date that the letter will actually be sent.
In writing authorization letter, you have to mention - I hereby authorize (the name of the person) to (Purpose of giving the authorization) on my behalf. You also need to state, a valid reason why you need to authorize the person or you have to mention the reason for your absence. You also need to sign the documents for record and reference purposes.
Most people Understand
What ever you want to use
When writing a letter, it is appropriate to use Mr.
Mevrouw
Calligraphy is used for fancy writing for like a love letter or just a letter
I hereby request you to issuing the transfer certificate.
Use Microsoft Word
You are writing a business letter, you should be more formal.
respected
Pineapples