Hello,
First of all RIP for your father and wishing peace on his soul. I am Prasun, the project coordinator of Webgen technologies. I will be managing the project and will be communicating you all the way.
I have seen the GETSY Clone script from Etsy and I see that it has most of the the features you have requested, but not all. For instance,it does not have the option of choosing cutom product templates. Although it has an option of multi-store, it does not allow you to customize the store template like eBay. Also, the GETSY Clone script does not seem to have an ad management platform. But on the brighter side, it does have most of the crucial features such as adaptive payments, internal messaging etc.
So even if you use an off the shelf solution (Etsy or anything else),we will still need to custom code a lot of things. However it would be cheaper than scratch development.
I have been through your listed requirement details and as per my knowledge Day by day Pinterest is going to be world's no1 clicking site, it has already reached 30 billion pins. And I believe I will be the integral part of it's competitor website. However,The phases you talked about are fine to work with . I will be brief with some key notes of the project we will be focusing: IMAGE-recognition technologies Cross platform and browser compatibility Image Tagging #HASHTAG TRACKING like instagram Facebook analytics IMAGE SCHEDULING Send Pin to your friends Pin notification Extended Repins etc
Thanks