Can someone help me with my site structure? Sections/Category setup
It's fairly straight forward. You could go with a single "layout" file and then a template file for each unique template that utilizes that simple header/footer layout


templates/layouts/_layout.html 
templates/index.html (homepage)
templates/products.html
templates/support.html
templates/contact.html


Extending a layout:

{% extends "layouts/_layout" %}


Your product template would then just need to be coded to handle the category handle in the URL.

For instance, listing entries (products) that are assigned to a category (untested):

{# get categorySlug from URL segment 2 #}
{% set category = craft.request.getSegment(2) %}

{# get instance of category #}
{% set category = craft.categories.slug('categorySlug') %}

{# get entries related to the category instance #}
{% set entries = craft.entries.relatedTo(category) %}

{# loop through the entries #}
{% for entry in entries %}
    &lt;a href="{{ entry.url }}"&gt;{{ entry.title }}&lt;/a&gt;
{% endfor %}


That's obviously just an example, but should get you going in the right direction.

Related reading material:


https://craftcms.com/docs/templating/craft.request#getSegments