Please, correct my letter!

Hello!
Excuse me, I cannot connect with you in an official e-mail!
Our portal *** writes about mobile applications, application development and mobile marketing. We would like to ask you a few questions about your product .
We would be grateful if you could answer our questions and inform us when you can do it.
Yours faithfully,
Waiting you,answer,
Kathrin

Please, correct my letter!

Hello!
Excuse me, I cannot connected with you in official e-mail!
Our portal *** writes about mobile applications, application development and mobile marketing. We would like to ask you a few questions about your product .
We would be grateful if you could answer our questions and inform us when you can do it.
Yours faithfully,
Waiting your answer,
Kathrin

Please, correct my letter!

Hello!   

Если Вы знаете фамилию человека, которому Вы пишете: 

Dear Mr. X:  //  Dear Ms. Y:  

А если Вы не знаете:  Ladies and Gentlemen:

I am sending you this letter because I have been unable to contact you via official e-mail.
Our portal, ***, contains articles about mobile applications, application development, and mobile marketing.  We would like to ask you a few questions about your product.  [Если есть более чем один продукт, то пишите products.]  [Именно здесь подходящее место, чтобы включить в письмо вопросы, которые Вы хотите задавать.]
We would be grateful if you could answer our questions, and inform us when you can do so.   
I look forward to your reply.
Yours faithfully,
Kathrin [фамилия]