Hi Jűrgen

Just to add onto what Lars has advised.

(Q1) There are two ways to play on your Android phone. The first is to use the Chess for Android app or Certabo's own CertabOdroid app which is basically the Droidfish app. It does not work wirelessly and you will need a OTG cable.

(Q2) Don't know

(Q3) The Certabo PC software 3.3 includes MessChess but you will need to provide all the chess computer ROMS from Franz excellent CB-Emu program. PC only not IOS or Android.
You can also use Lars Certabo UCI driver as described on the Certabo web site which in my opinion works a bit quicker than the Certabo software and of course can be used with other chess software like Shredder etc.

Hope this also helps but if you are still a bit confused then just contact Pietro at Certabo. He is very friendly and helpful.

Regards
Bryan