Upgrading from Shopperpress 7.1 – looking for advice

Just recovering from getting all my sites hacked, obviously now looking to install the latest theme versions. I haven’t updated my Shopperpress theme since 2012 mainly because I had a lot of problems the last time I upgraded. Now the Shopperpress theme is no longer supported so I am looking at upgrading to the new responsive themes.

The site is a digital download site (ebooks, articles, software, etc). This is the site

https://www.marketerswarehouse.com/category/all-products/

There are over 5,000 products on the site. So my questions are

1. The WordPress Digital Download Theme would be my best option right?
2. As you can see from the site I have a lot of categories and subcategories. Does this theme support subcategories?
3. Are there any major functions absent from the new theme that were present in the old Shopperpress theme?
4. Is the upgrade path straightforward especially do the product listings transfer OK into the new theme. With over 5,000 products I really don’t want to have to go through each one and edit them because the formatting has messed up, images no longer show, etc

Apologies for asking so many questions but I want to know what I’m letting myself in for before upgrading and would greatly appreciate some feedback!

Many thanks

Robert