Divi Booster is a good option to get that added functionality without having to code. Divi Switch is another really good, and comparable option. Hard to say one is better than the other. In fact, you can run both at the same time. It comes down to evaluating your needs vs their features. But ultimately, both are solid choices.

Many drop ship. Many buy and hold inventory. It truly is a mixed bag and depends on how you choose to operate.

This could potentially work. You could run the sales as daily flash sales, letting buyers know about the purchase thresholds that have to be met before a sale becomes final. I think if you didn't run these as flash sales with time limits, it could take too long for a given product to reach it's threshold. People want their stuff fast. The flash sale concept would both encourage purchase via natural urgency, and enable the sales to be finalized and processed quickly.

If you can guarantee manufacturers that you'll hit their minimums, they will be likely agree to this as long as they are okay with drop shipping the sold goods.

Here's what I would do. Find and vet one good specialist. Perhaps for just one of the platforms. Have them at the ready and tell they they'll be paid per job. Validation comes when someone hands over their money for your service. I'd then share and promote the service everywhere I could. I would do it founding members style... meaning, I would promote that I'm launching a new service and looking for a few founding customers to help me shape this into the perfect service for them. In return they'll get a deeply discounted founders rate, which will stick with them for x amount of time. If you get a few buyers, you have validated the service. You connect the buyers with your specialist manually and off you go. Don't need a website for any of that!

Statista is a good source. For example, one of their reports states that for global internet users, the largest percentage people of who have made online purchases (58
%) were in the fashion-related category.

Here's a good start on all ecommerce stats for apparel. https://www.statista.com/search/?q=apparel

I'm an ecommerce and digital marketing professional and also have many years experience in web development.

I recommend going with a WordPress based site, because there are many available themes already, and a huge community of developers that can customize them without much difficulty.

Here's a great list of Groupon clones:
https://wplift.com/groupon-clones-daily-deal-group-buying-wordpress-themes

5 good examples of Kickstarter clone themes:
http://www.wpsolver.com/kickstarter-clone-themes-for-wordpress/

Clones of wish.com seem to be a bit harder to come by. Here's a non-WordPress one called Shopr https://www.appscrip.com/wish-source-code-for-m-commerce-ios-android/ - It's based in Angular which is a fast and well supported new web framework.

if you are interested in being a tour guide in the United States, you might be required to earn professional licensing, depending on which city or area you want to work in. If you plan on being a guide in any of the following cities, you will need to get licensed first:

Washington, D.C.
New York, NY
Savannah, GA
Charleston, SC
Gettysburg Battlefield, PA
Vicksburg Battlefield, MI
New Orleans, LA

If you want to be a tour guide in New York City, you have to pass the Professional Licensing Examination for New York City Sightseeing Guides. The test consists of 150 questions, and you need to answer 97 correctly. The questions cover topics such as New York transportation, history and architectural landmarks.

Becoming a tour guide in Washington D.C. requires submitting an application, which includes completion of the Professional Sightseeing Tour Guide Examination. You'll also need to be able to communicate in English and have a clear criminal history over the last five years.
Source: learn.org

I don't do much print design, but I was just helping an associate look for some tools like this. Both of these are online tools, and allow one (or more) page creation.

Adobe Spark looks like a good one! https://spark.adobe.com/make/brochure-maker/

Brochure Maker also looks pretty slick!
https://www.befunky.com/create/brochure-maker/