I could answer the last one for sure. Yes, crossover has been already registered.

With respect to the first question, I remember there's an advanced option in the installment ISO when we boot into it. It's a kind of a live ISO.

The last question about Crossover. Good. I've installed it in two other distros. Not that I'm going to use it to work with Windows apps, only to check if I can install it in other distros. I'd use windows for Windows apps, as Windows usually comes with the laptop.

Regarding the first question, I'm writing this from the live iso (created by me), which is about 1.8GB. (And, the 2nd question)
Btw. I haven't installed Deepin 15.2 yet. As its based on Debian, I'm thinking, whether its worthwhile to fork it.

Well I didn't see a Live version!  If there's something in the advanced installation options I will have to look again.

I only use Windows for a a few games on occasion, as far as APPS go there are good Linux versions or equivalents that do just fine at what I need them for.

Vbox might be better for some Apps still.

There is nothing wrong with Debian I've been running it for over 10 years.  Its stable, solid and keeps a familiar interface design.  Don't forget a 1/3 maybe more Distro's use it for a base.  So you take that away most of these including Deepin would never exist because Debian already did 90% of the work.  Maybe every one forgets that Ubuntu is Debian at the core.  And a lot of new distro's start out using Ubuntu for a core and switch to Debian.  Basically all they are doing  is removing Ubuntu tweaks and desktop redesign and dropping it in favor of their own once its matured enough.  Removing any  possible Ubuntu bugs.

My question is why there isn't a Live version, when it can be done. I haven't installed Deepin 15.2 still, only using the "my" Live version from a USB stick. At the moment, it is about 1.8GB, but I think it can be made smaller.  

When start installer? do it next:
ALT-F2.
LANG=EN_en.utf8 startx
Welcome to Deepin live!
)))