By Business letters, Apostrophes

I am college freshman writing a business letter for my dad's business oversea. I'm doing so because no one at his place speaks/writers acceptable English. So, I am drafted to write a letter (not e-mail) for him to a big company requesting for partnership. The my dad's marketing manager sketched...

Question I: Number (2) has too many 'what's, and 'gonna' is unacceptable except in slovenly spoken language. Number (3) would only be useful in limited contexts: 'you never know what happens next until after you've seen the movie'. (1) and (4) are fine are fine for general use, as is (2a)...