I discovered today that the character map which comes with this version of Windows is larger and arranged differently than the character map on Win versions I have used (the one I'm using now at home is Win98).

It's called Unicode, and it's a great and wonderful attempt to provide character mappings for most of the world's languages. There's a website for further information:

http://www.unicode.org/

Ðð Latin eth

Also called edh. It's basically a barred d. Still used in Icelandic and Faroese.

the caron is an upside down circumflex written over a letter

Also called a haček in Czech.

the ogonek is a small mark

I always thought it looked like the comma-like part of the cedilla ç ... It usually represents nasalization of a vowel in Polish, sort of like the tilde in Portuguese.

how do you get a computer to write right to left if you want to write in Hebrew or Arabic? Or here's another question I would be glad to be enlightened on: how do computers write in Chinese or Japanese or other pictographic systems?

Well, how can the computer write left to write? It's the same thing, except you switch the directions. Actually, it's now part of the OS, and you have to set things up to work that way. (You can use both directions in a single sentence or paragraph, and it gets kind of confusing.) Sino-Japanese characters are just like other glyphs in character mappings. If you mean how can you type them, there's a bunch of different entry methods: e.g., when I was learning Mandarin Chinese and typing up flashcards for study, I used the Pinyin system which is a phonemic system using Roman letters. There are others that are stroke based. If you look in your control panels, there's a Keyboard control panel that has an Input Locale tab. You can add different keyboard configurations for different languages and different entry methods, etc. You might have to load different fonts, keyboards, etc, to get things working, but most modern OSes have support for a great many of the world's languages. Hope this helps.