...but I think the Unofficial Guide for 
Disneyland has a section on Universal.  Fodor's also has a good guide for the area that includes Universal. 
As for characters...they're rare, but they do pop up here and there.  I remember seeing Woody Woodpecker.  And I think some of the Rugrats kids drop by.  But they aren't nearly as plentiful, or as familiar and beloved, as the Disney ones.  
Generally, I think, Universal is not geared as much to kids; most rides are linked to thrills or to the movies, and wouldn't appeal to little ones.  (A notable exception is "ET" -- which bears a more-than-passing resemblance to "Peter Pan's Flight" at DL, but is more intense and realistic, I think.)
<font color=blue>
<font face="Alaska">"It's the time of your life, so live it well..." 
Greg K.
Forest Hills, NY
Grand Floridian: '96,'97,'99
Disneyland Hotel: '00 </font>