Shopify UI & Theme Tweaks

I need an experienced Shopify developer to tidy up a handful of interface details across my theme and keep everything completely dynamic, so I never have to edit a product record manually.

1. Shop by Car page
The “BRANDS & CARS” thumbnails should behave just like product cards: when a visitor clicks any image it must open the corresponding brand page (not a product page or a popup). Please preserve existing responsive styling.

2. Header on the Home page
a. Add a toggle switch that lets shoppers jump between light and dark mode. The switch should inject a dedicated dark-theme CSS file and remember the visitor’s choice with localStorage.
b. Insert social-media icons in the same header bar and wire them to the live profile links I will provide.

3. Product pages
a. Global carousel: under every product, load a dynamic, auto-scrolling carousel that pulls only from my “Cleaning Tools & Utility” collection and labels the section “Frequently bought items.”
b. Product-specific carousel: add a second carousel that automatically detects the car collection attached to the current product and shows related items from that collection.
c. Below the buy box, replace the static text blocks with accordion dropdowns titled Warranty, Return, Replacement and Shipping, each revealing the relevant policy text when expanded.

4. Technical note
All of the above must be driven through theme code (Liquid, JSON templates, JavaScript) or metafields so no edits inside individual product records are ever required.

Please let me know if you need theme access details or example brand/collection handles to get started.