Is there a minimum gib required for downloading the "pro" version as opposed to basic "core"? Will a 4 gb drive be adequate for both?

I'm new to Zorin, and I have to do the process pretty much on my own. So, I want to prepare for this process to make it run smoothly. I've seen a few videos, and I think I get the general idea - but my concern is comparing the pro version with core. The question is about memory requirements on the boot drive. I have a 4 gb drive, and I wonder if that will be enough storage for the pro version.

I could be wrong but I believe it takes 4gb for basic and 8gb for Pro ... but maybe someone else will know for sure ....

Pro comes with more installed applications and layouts.... but the RAM requirement really should be the same. 4Gigs is a little on the low side.

Is there a good tutorial video focused on the pro version download? Also, is there extra "support" with the pro version? How exactly do you access that support?

Probably, though I have never looked for one. There is a video for pretty much everything on the interwebs...

Zorin OS Pro comes with Installation Support. When you receive your download link for Pro, it comes with the Support Email address you can contact.
Or, scroll to the bottom, here:

EDIT:
Crosslink-

Did you mean RAM or the size of the USB stick?

size of USB stick. Is 4 gb enough storage to download the pro version?

No, sorry, it is not enough capacity for the USB stick.
I believe the Pro Download exceeds 7gigs. I honestly would not use an 8gig stick, either. 16 gigs would be safer.