Help with my daily writing

Industry: Technology
Topic: various
Tone: Informal/Casual
Outline & Structure: I need someone to help me with my daily writing.
I'm a quite advanced English learner, but I want to improve my writing skill in order to think and write more natively.
So I'd like to find a writing tutor, the way I expect you to work is,

1. I will send you a piece of my own writing by email. The topic could be anything, an email, a short article, etc..
2. You will give me responsible feedbacks of my writing, including grammar, the way of expression. If necessary, rewrite some of the sentences.
3. I may ask some related questions and expect you to answer in the further emails.

The length of writing will normally not exceed 500 words per piece of writing, or 1500 word per week.

I'm looking for someone who has good communication an writing skills, preferably has some experience in tutoring.
And can answer to my email fairly promptly ( I will not expect you to always respond in 2 hours, but maybe in 24 hours ).

Please give me a weekly rate that you think is appropriate .

Thanks
Extensive research needed: no
Extra notes: