THEME:   Periodic table abbrs. are substituted for the names of elements in phrases   
GOOD ONES:     Pirate once portrayed by Orson Welles  
LONG JOHN AG [AG = silver; my favorite portrayer was Robert Newton]   
Dickens classic   
DAVID CUFIELD [CU = copper, I guess; I forgot much of my chemistry]   
"High Voltage" band   AC/DC [indeed]   
It's sometimes held in a deli   MAYO ["Hold the mayo!"]   
Inside information   X-RAY   
Sites for sweaters?   SAUNAS [DRAWERS didn't fit]   
Target of a military press   DELT [don't know when 
delt became it's own word and not an abbr., and I'm not sure why the press is military, but a press in weightlifting can develop one's deltoids]   
State of disbelief?   ATHEISM   
Making an impression   DENTING [probably a bad one]   
Rapper's demand   LET ME IN [I thought more "Raven" than vocalist]   
Carrier units   AC'S [I thought ships]      
BTW:   Him, in Le Havre   LUI [but not in Leeds]      
Alike, to Pascal   EGAL [this French word is grist for our mil as it is part of their motto which is often used in English; however, it means 
equal which is different from 
alike]      
1987 "Crying"…   LANG [she's k.d.lang and has one of the best alto voices on record, and while the duet with Roy is great, her solo version is so powerful it brings tears to my eyes]      
CURDY? If you insist.      
Hardly paparazzi quarry   D-LIST[there is no D-list among the famous.  To be on any list would be quarry.  Clue should be like "Third grade naughty kids"]      
Thunder predecessors   SONICS [I suspect this definition refers to physical waves produced by lightning which creates the thunder, but my physics isn't much better than my chemistry]      
Today's title "Elements of Style" is also the title of a classic in the writing of English --- more my speed than elements in chemistry. But the puzzle could not have been more fun.   
RATING: 
 
  
  
   Three grins = Loved it; Two grins = Enjoyed it; One grin = A bit bland for my taste; One teardrop = Not much fun