If you are using Chrome Hannah then I recommend "DuoKeyboard" (Google store), the add on switches the keyboard depending on the language Duo needs for the answer.
I have been using it for a couple of months and it works very well - except I occasionally miss key υ as θ (the keyboard is correct - I am wrong).
It is really cool to be able to type answers at reasonable speed in Greek without fiddling about with keyboard changes - and the Greek γράμματα are so beautiful!
I don't know how to add accents on the Greek keyboard.
On a Mac or PC: try pressing the key to the right of the L key (where the semicolon ";" is on a US keyboard), then the vowel.
On a mobile keyboard: try long-pressing the vowel key.
And the accents are part of the spelling: for example, που is not the same as πού, nor κυρίων the same as κυριών.
A question to the pronunciation of "kai" (and) Does the "k" sound like in "kappa" at the beginning of the word?
The phoneme /k/ has two allophones in Greek: velar [k] before back vowels /a o u/ as in κάππα but palatal [c] before front vowels /e i/ as in και.
Since they're allophones of the same phoneme, a native speaker may tell you that they "sound the same" (just like a native English speaker may not notice that the /t/ in the words "top" and "stop" are pronounced differently).
"k" in "kai" hört sich dann eher an wie "ch"?
Nein. Es ist ein palataler Plosiv (Verschlusslaut) [c], kein palataler Frikativ (Reibelaut) [ç] wie im deutschen Wort ich.
Griechisches palatales /k/ ist zum deutschen "Ich-Laut" wie griechisches velares /k/ (oder deutsches /k/) zum deutschen "Ach-Laut".