Opencart product page and category page customization

I have an opencart site , my current developer is out for some time , I need 3 points done . 1. Need to set category >> subcategory structure. In these when you click on category it will show the another collection groups of products in the place of product listing and when you click on that collection group you will found the product listing of that collection group. 2. Can you please change: Inquiry form for product page popup Choose Model to Fabric Options in product detail page we need to show selected options for product in inquiry form as well and it will go in email too. 3. Custom options should work like this : For example they have two model:K grade leather and W grade Fabric. So when we click on Model name price should be changed. but in our new site its changed on each custom options. For example Product price is : $13.00 and suppose price of Storage is $15 then total should be $13+ $15 = $28.00 so in short price changed when you click on Model name(fabric options.) I can explain points in more detail and can provide you website details . Thanks for reading .