WordPress-Based E-Commerce Bike Store Setup

I need help making with a wordpress with a store widget or not sure if it should be a shop as Shopify or other. We must agree which we will use I have worked with other Wordpress sites but not recent with online selling.
Is for a Bikestore.
We want something light that runs fast, ready for SEO.

I imagine it this way:
1. About us.
2. Contact Form
3. Products which is divided into different categories:
- Clothes (divided into groups such as jersey, bibs, socks, accesories) also divided into man and women.
- Bikes (divided into categories as Road, Gravel, MTB). Each bike have a list of features (components, wheels, frame type, ....) and must have a way to compare between selected bikes.
- Accesories

Take in considerarion:
- All work should be in our server, you could work in any where but before releasing payment should be in our server and includes all the next info:
- Easy way to backup test and upload to real site.
- For each product we have options: Color, Size
- Ready for SEO
- We must have a way to select a stripe or paypal account to use. The one with less % deduct. And hooe we could have a sandbox to test.
- Easy to change "theme". Since for now will use one brand. But we may change it inna few weeks to another. That means new background, Title, and some others.
- Our main language for the site should be Spanish (we don't really need other, but could be if you want).
- we expect to receive instructions on how to configure everyrhing.

I NEVER release money until everything is finish. Don't waste each other time asking to release milestone until finish.
If you read all mention word CHOCOLATE to know you really read it.