Customization on word press theme

I have this URL www.sticherry.com. A Word Press is already installed on this website. Now I want to customize the website according to needs. The customization required is quite basic such as uploading pictures with description, putting information on contact us page and stuff like this. I will give the exact details later on. Also the website requires one very imp customization which is: The customer should be able select a dress un-stiched or stitched before adding it to the cart. If the customer chooses Un-stitched, then she will only have the option of selecting colors but not the size. If the size option cannot be disabled at this point in time, it is ok. We can work on this in due course. If the customer chooses stitched, then it will have the option of selecting colours and the size. In size the customers will have the option of selecting Small, Medium, Large or Custom Size If the customer chooses custom size, then we should ask the customer to enter 6 different fields. Shoulder Size, Chest Size e.t.c. I also have the example of what I want. The job is not tedious at all. I will tell what exactly needs to be done before I award the project. I want someone who is efficient, fast and most importantly who has worked on clothing websites before. The developer should have the basic understanding of the website.