E-commerce Website design/development

General information for the website: Selling Horse saddles online
Kind of development: New website from scratch
Num. of web pages/modules: Various
Description of every page/module: Please see my existing website for an idea on content. But note that I will need new features as it does not work as it is. www.thesaddlebank.com
Description of requirements/features: Please see my existing website for an idea on content. But note that I will need new features as it does not work as it is. www.thesaddlebank.com
CMS and Admin requirements: Please see my existing website for an idea on content. But note that I will need new features as it does not work as it is. www.thesaddlebank.com
Payment methods: Credit Card, Paypal
Similar urls: https://www.sheephamsaddles.com/ https://www.saddlesdirect.co.uk/
Extra notes: I have a beyond basic Vistaprint website at the moment! Designed by me - Yep I have no idea about all this IT stuff.
However, I am looking for something with better functions.
I would need to be taught how to upload new stock, as the stock as individual one of items, so are changing regularly.

I want it to have a search facility, where customers can search by brand, size, type etc, and then it bring up those items.

I would also like a screen to pop up when they come onto my website where I can capture their email address for future marketing.

I like simple, easy to use designs, that enable photos of the products to be enlarged. Each product may have 8-15 photos, and a description.

I can show some examples of similar website's.

NOTE: It is crucial that I am able to update the website once it has been developed, as stated I have to make regular changes.

Please contact me to discuss.
Please explain to me in simple terms what you are offering as I will not understand if you hit me with loads of techy words. :)