Just simple question:
Is the version of Arena on GOG floppy disk one, CD-ROM one, or Deluxe Edition?

Version 1.07. There is a thread here: "What Version of Arena and Dagger fall should I play?" from November 2017.

So basicly it is limited deluxe edition with newest patch (1.07), with Codex Scientia (of course, only .pdf file, not printed one), but without mouse pad with Tamriel map printed on it.

... and it also doesn't have the paper version of the manual :-).
The most comprehensive collection of Arena maps I'm aware of is there: [url=http://en.uesp.net/wiki/Arena:Maps]http://en.uesp.net/wiki/Arena:Maps[/url].
It contains the map shown on the mouse pad (second from top).
And here is a similarly comprehensive collection of Arena files: [url=http://en.uesp.net/wiki/Arena:Files]http://en.uesp.net/wiki/Arena:Files[/url].
Unfortunately GOG doesn't ship the nice cloth mouse pad with the free game indeed, alas ...