Moving from Snapshot Premium to Vantage

Hello!
As a loooong time user and super fan of Snapshot Premium, I am seeing that Vantage has some of the items covered that SP may be lacking. Specifically Woo interface compatibility and the more responsive aspect of mobile.
Question:
1. Will the mobile responsiveness be a plugin widget – thus slowing down my site speed? Or is it built into the theme itself as recommended by google when it tests your site for mobile ease of use?

2. Is there a Vantage Premium? If so, what are the extras for premium use ie purchase?

3. I have been extremely pleased with the help I have received from the support staff at SO early on when I first encountered Snapshot Premium – if I choose not to use Vantage, are you still planning on supporting Snapshot Premium owners?

(I have signed up for the newsletter and want to give all of a kudos for the great work you are doing, such as the widget bundle).

4. What specific areas, if any are known, will need adjustments from a snapshot theme to a vantage theme?
(I can see I will need to refresh my memory cells on how to increase my overall website text font, if I go with Vantage) …. of course that may be because i am as oldasdirt.