I have not done it, but I don't remember hearing any problem with Dragonfly on Windows 10.  Seems like it should work, but maybe I'm missing something.  Do you have a source for that?

Dragonfly is open source.  The community isn't huge, and the orginal source is many years old.  The documentation is good, but fragmented, and if you follow it, you find errors here and there.  I love it and use it extensively, but my point is, unless you're already a decent programmer or excited about a significant project and learning curve, it's probably not what you want.  As Lunis pointed out, Dragonfly doesn't work with the latest version of DNS (v.15), and we have no idea if this issue with ever be fixed.  So, if you decided to jump in now, you're taking a risk that you won't ever be able to upgrade your DNS version.

All that said, there are a lot of reasons why some people have favored the various open source, NatLink-based solutions (Vocola, Unimacro, Dragonfly, ?) over DNS's Advanced Scripting.  A big one seems to be continuous command recognition.  As far as I know, you can't do this with DNS's Advanced Scripting.  There are a ton of other reasons, too many to list here.  For me, avoiding VBScript, using a non-proprietary solution, having complete access to the Python ecosystem of libraries, are a few.

In terms of "pre-defined commands":  I don't think that installing Dragonfly will create any pre-defined commands.  Many people, however, have created and published numerous command modules for dragonfly, modules you can copy/re-use freely.  You can find some examples here:

http://dragonfly.readthedocs.io/en/latest/related_resources.html#command-modules

A few other Dragonfly resources:

http://dragonfly.readthedocs.io/en/latest/index.html

http://caster.readthedocs.io/en/latest/caster/doc/readthedocs/Voice%20Index/

- a treasure trove of info and links on dragonfly and related