Graphic design

I need two cartoon like characters developed. Time line - i would like to have the finished product by end of September. I will need ongoing work and revisions as business develops (and dependent) on how business develops, but this is only likely to be in the new year. I need to own the characters, but am happy to establish an ongoing relationship with an artist for revisions.
I also need a logo... And would pay additional for this too, again, I would need to own it.