3. This is why your shell has wildcards.
It's nice to be able to know what the name of a file is before deleting it - it may give some idea about whether it should be kept or not.
2. Putting non-ASCII characters in filenames is an even worse idea than putting spaces in filenames. Don't do it, and you won't have problems.
I don't do it. The users on systems I (hypothetically) maintain may not be so considerate. Especially if their first language is written in a different alphabet.
1. You should have consulted a table of Linux-compatible keyboards before you bought your keyboard.
Or perhaps consult a Linux compatibility table before deciding to be born into a country with an unsupported language? Or are you suggesting that everyone should keep two keyboards, one for the language they use all the time, and one for Linux console use? (In practice it wouldn't help either, because Linux supports virtually all keyboards in desktop environments, so your compatibility table would likely say "yes" even without full console support.)