I have a site which has both engligh and some french chars in the 40MB database

I and finding some greek characters are not working properly.

I have 3 general questions, as my research leaves me still wondering

First: My method is posting chars like ди directly from html form into mysql ie, I'm not encoding them to äè

Q1. Is it a problem to just convert my mySQL databse (* tables) to utf-8, and whats the best methed (Is it a risk to just change the encoding in phpmyadmindrop down).

Q2. If you want to suppory diff chars like chinese, german, french, greek etc etc are you better to have seperate tables set up with proper encodings or whats some methods for this. I have a site that is slowly turning global and requests for diff languages are coming in.

Thanks
Trent