php - How to pull cyrillic data from SQL as array and use str_replace()

Question

I have the code:

mysql_connect('...');
mysql_select_db('...');
$result = mysql_query('SELECT `oldword`, `newword` FROM `#_words`');
$find = array();
$replace = array();
while ($row = mysql_fetch_assoc($result)) {
 $find[] = $row['oldword'];
 $replace[] = $row['newword'];
}
$oldstring = 'Some text';
$newstring = str_replace($find, $replace, $oldstring);
echo $newstring;

It works good but there are two problems. First I need to convert it for using Joomla API i.e. to something like

$db = &JFactory::getDBO();
$db->setQuery('SELECT `oldword`, `newword` FROM `#_words`');
// and what is next, what about mysql_fetch_assoc ?

And secondly, if oldword and newword are english it works but if cyrillic it doesn't. How can I fix it? I have tried this:

function fixEncoding($s, $encoding = 'UTF-8') {   
 $s = @iconv('UTF-16', $encoding . '//IGNORE', iconv($encoding, 'UTF-16//IGNORE', $s)); 
 return str_replace("\xEF\xBB\xBF", '', $s);
}
$find = fixEncoding($find);
$replace = fixEncoding($replace);

but this function works with a single string only and doesn't work with array