Product Type Collections & Tags
Well as always with Craft there are many ways to skin this particular cat.  

A simple approach would be to have a catalogue template (either just one for all product types or separate ones for each product type if you want to vary the format significantly).

Assuming just one template for your various catalogues, this could live in your  templates folder at e.g. _site/product-catalogue.html

You could set up a route in Settings->Routes, such that 

*/catalogue pointed to  /_site/product-catalogue

this template would then load whenever someone went to e.g.

yoursite.com/monitors/catalogue

In there you could query for all products of that type and display them:

{% set segment_1 = craft.request.getSegment(1) %}
{% set products = craft.commerce.products.type(segment_1).find() %}


...and proceed from there any way you like, really, in terms of display.

In terms of building you nav:

{% for productType in craft.commerce.productTypes %}
    &lt;li&gt;&lt;a href="/{{ productType.handle }}/catalogue"&gt;{{ productType.name }}&lt;/a&gt;&lt;/li&gt;
{% endfor %}


(Another approach would be to add all the products to a category, and then use category fields and a category template to display your product list).

I haven't used tags much, and I am not sure I'm 100% on what you're asking (do you want to highlight sections with new products, or create an extra element in your nav for these?)....but in essense you'd probably have to search for products in that category and look for a tag of New.  Here's some sketch code:

{% for productType in craft.commerce.productTypes %}
   results = search for entries with this type that have the tag New
   if the length of results &gt; 0
      &lt;li&gt;&lt;a href="/productType.handle/catalogue"&gt;*** NEW *** {{ productType.name }}&lt;/a&gt;&lt;/li&gt;
   else
      &lt;li&gt;&lt;a href="/productType.handle/catalogue"&gt;{{ productType.name }}&lt;/a&gt;&lt;/li&gt;
   endif
{% endfor %}


Craft docs on doing the search are here: https://craftcms.com/docs/searching