Hiring hourly base employee.

Hi,
I have been blogging since one year and half. I tried my best to consider the blog as a job, and blog regularly, however as this is a DIY blog a lot of work is needed. This blog is related to the online shop I am intending to open. The success of the shop is strongly connected to the success of the blog.

Now I am thinking of hiring a girl (She is still studying in the collage) that I know to help me with the blog operation, like:
-Taking photos and editing them.
-Creating videos.
-Creating the online shop.
-other technical stuff.

For the time being I don't have an office to share it with here, it will only be some meetings in a coffee shop to delegate the work to her, and I will rent a room for photo shoots.

I didn't contact her yet, but I would like to ask, what should I write in the email?
Should I mention the hourly rate? I am not even sure if it is hourly rate, or project base? I am undecided.
Should I ask her about her hourly wage?

What do you think? I need your help, it is my first time to hire!:confused: