Need a few t shirts designed.

I have a few ideas for shirt designs for my business and would like to know:

1. Cost per project (I have between 5-20 designs in mind).
2. What you need from me? I'm not an artist but have specific thoughts in mind
3. What is the turn around time?
4. How would I use these designs for shirts (transfer? digital? etc.)
5. My main design would be a pocket logo (ours) with a design on the back. For some of these I have my own pictures. Some will need some digital artwork.

Thanks, Jaime