Schema for Ecommerce Website

What are the mandatory schema, well there is no mandatory schema you have to use.

Resources you will find useful:

 https://search.google.com/test/rich-results  -  To test a page and see if its eligible and to see any warnings or errors in your rich snippets.

I would suggest you use the following schema's

Organization

Product

Reviews

There are probably a few more you may want to use.. 

https://schema.org/ -- for more info on what schema types there are

Then use the Google testing tool on the # 1 competitors for your search terms and test their pages and duplicate what you see if it is appropriate, at least till you understand schema much better. 

An e-commerce website must have the schema for product pages and You can use Google’s Structured Data Testing Tool.

Schema.org implementation on an eCommerce website can give you extra stars and product information within the Google search results.

However it’s not completely straightforward to code yourself, and each eCommerce CMS has different best practices for adding it.

If you have multiple categories of products like you say, it shouldn’t directly change the way you add schema markup because the changes are usually made directly into the template itself.